Ashley Tisdale's legitimately freaked out ... after an obsessed fan sent more than 18,000 tweets to the actress and then showed up to her home, TMZ has learned.

Law enforcement tells us ... the LAPD has launched an investigation after a person in Ashley's camp reported that a super-fan had tweeted her 18,888 times, dating back to November, 2012.

The tweets are pretty creepy -- the person (believed to be a man) seems to be delusional, writing as if the two have some sort of ongoing relationship. For example:

"My body is yours & even as friends I f***in love how I make u feel like mom maybe we both got issues cuz nobody's perfect."

"I'll never lose u baby even in 20 years til infinity you'll always b my best friend."

"Let it all out on me u can have my heart put a lock on it throw away the key & my soul is yours to keep."

Even scarier ... we're told the suspected super tweeter recently showed up to Ashley's house ... but we don't know if he ever made contact.

We're told cops have identified a suspect -- and are looking to talk to the person to determine whether he poses a serious risk to Ashley.

Calls to Ashley's reps have not been returned.

Christian Chavez -- the telenovela star who was also in a famous band -- got in a fight with his ex-boyfriend that led to their arrest over a tweet allegedly showing Christian dressed up like a woman.

Sources connected with the case tell TMZ ... Christian's ex -- Ben -- told Beverly Hills cops they both went nuclear early Tuesday morning after Christian confronted Ben about posting a picture on Twitter allegedly showing Christian in drag in West Hollywood.

We're told Ben informed cops Christian was upset because he thinks the pic would be damaging to his career.

As for what happened in Ben's apartment Tuesday morning ... Ben told cops the two had broken up a month before ... Christian was still staying in the apartment and planned on moving out permanently on Tuesday. 

Ben said he woke up to find Christian videotaping him as he slept, which enraged him.  Ben said he took Christian's cell phone and threw it against the wall, breaking it.  Ben told cops Christian then retaliated by trying to take Ben's phone and damaging it.

The two started wrestling and punching -- each attempting to get the phone.

Ben told cops he tried to disengage by walking out of the apartment and Christian hit him in the back of the head and allegedly escalated things with some threatening actions. Ben claims he then locked himself in the bathroom and called 911.


Both men were arrested for domestic violence.  And we're told this isn't the first incident where cops were called to the apartment.  We're told in February police came after Ben claimed Christian threw a cinder block through a skylight (see photos above).

We were unable to get in touch with Christian.

It's not all love for the first major (active) pro athlete to come out of the closet ... NBA player Jason Collins has also been the target of online death threats since announcing he's gay.

The homophobic threats began appearing on Twitter right after Jason's big coming-out interview with Sports Illustrated. Among the venom ...

-- "Yous a dead f****t talkn on tv Boy."
-- "Listening to Jason Collins describe his gayness as 'beautiful' makes me wanna puke. And kill him."
-- "Jason collins comes out the closet! Kill that biiitttchhhh!!!"
-- "First jason collins say he gay.. Now he on espn w lipgloss on  kill him now !!!"
-- "Jason Collins should get the death penalty lol how u a 7 foot gay dude lol the west is crazy smh"

In the S.I. article, Collins says he doesn't expect everyone to embrace him ... but it's unclear if he expected this kind of hatred.

We reached out to Collins for comment -- so far, no word back.

Two hacking groups have taken credit for launching cyber attacks against the AP and the White House ... but the perps are connected to the core ... TMZ has learned.

The Syrian Electronic Army (SEA) claims they "owned" the AP after successfully hacking into its Twitter account and posting a fake item that President Obama was injured in an explosion. According to reports, SEA has hacked Twitter for months to spread political messages. 

Exposed, the group behind most major celebrity swattings, is flying its flag as the team behind today's 911 bomb threat directed at the White House.

Sources close to the investigation tell us, the two groups are actually connected and have members working for both operations. Our sources say Exposed came out first to claim responsibility for the fake bomb threat.  As we've previously reported, Exposed has taken credit for more than a dozen celebrity swatting calls.

As for why SEA took credit for the AP prank ... it's unclear.  What is clear is that the prank was coordinated between the 2 groups -- a 1-2 punch, if you will.

The hacker group that claims responsibility for exposing private financial information about Michelle Obama and many other celebrities has issued an ultimatum to the U.S. Government -- either declare war on North Korea or they will detonate bombs at the White House ... TMZ has learned.

We're told the group -- which claims responsibility for swatting Rihanna, Diddy, Ryan Seacrest, Justin Timberlake, Paris Hilton, Chris Brown, Tom Cruise and others -- contacted authorities through 911 and threatened to detonate 8 devices around the White House perimeter if President Obama does not declare war within 24 hours.
 
There was a tweet that went out on the Associated Press' twitter account saying, "Two Explosions in the White House and Barack Obama is injured."  The White House quickly discredited this as an "errant tweet."  We're told the hackers are claiming credit for hacking AP's twitter and posting the message.

It appears -- though it has not been confirmed -- that this is yet another case of swatting -- calling in a phony threat.

 

Legendary ventriloquist Jeff Dunham can sleep soundly again ... because we've learned cops have neutralized the person who made multiple death threats targeting him.

According to legal docs obtained by TMZ, L.A. police recently executed a warrant to search Twitter records for the identity of a user who threatened the lives of Jeff and his family.

Among the tweets ...

-- "Wanna go scare some kids?? Maybe kill 'em too? I'ts all yers buddy [sic]."

-- "YOUR NEXT ON MY LEEST ... Guess who's outsideeeee"

-- "You have approximately 4 months b4 death ... CHOOSE what you WILL do b4 you DIEEEEE...."

-- Then to Jeff's wife ... "Your husbands name was spoken ... 4 months is his limit ... of DEATH ... I WILL DRAG HIM INTO MY CAPTURE ...."

Law enforcement sources tell TMZ, cops tracked the creep down and they're confident he's no longer a threat.  Our sources wouldn't be more specific.

The only thing that stinks more than horse dung is Miley Cyrus' stance against horse-drawn carriages ... that's according to the carriage owners who are pissed the pop star is trying to shut down their biz.

Miley tweeted her support earlier this week for a petition that supports the ban of horse-drawn carriages in New York City ... which didn't go over too well with the folks at Carriage Operators of North America. 

Tommy Doyle, a member of the Board of Directors for CONA, tells TMZ there is no horse abuse in the industry and that the animals are "properly tended to" and "very well taken care of."

Doyle says, "How many times has Miley spent with working horses? Does she even know what a healthy horse looks like? Has she been in the barn to see these animals?"

Doyle tells us Miley has an open invitation to come see the horse carriage business up close.

But from which end?

Evelyn Lozada fired off a cease and desist letter to ex-hubby Chad Johnson ... warning him to stop harassing her online ... OR ELSE.

Sources close to the "Basketball Wives" star tell TMZ ... Evelyn's lawyer sent the letter Thursday after Chad BLASTED her on Twitter ... making crude comments and accusing her of cheating.


Sources close to Evelyn tell us ... Chad's Twitter allegations are 100% false -- she NEVER cheated and if he doesn't stop spreading lies STAT ... she'll get a restraining order.

Not only that, we're told the prosecutor's office overseeing Chad's criminal domestic violence case is aware of the situation and is concerned.  We broke the story ... Evelyn filed for divorce after Chad was arrested for allegedly headbutting her just weeks after they got hitched.

Chad is due in court Monday for a hearing on terminating his probation early.  The Tweets are not gonna help his case.

You've seen the sexy chicks, now it's time for Guys with iPhones: Celebrity Edition. Try and guess which famous dudes couldn't resist from taking -- and posting -- shirtless pics of their own worked-out bods.

#gpoy.

If you've ever wondered what an Amanda Bynes mating call sounds like ... wonder no more -- because she is begging Drake to slay her genitals ... to put it delicately.

What Amanda said in a tweet last night was ... "I want Drake to murder my vagina."

I want @drake to murder my vagina

— Amanda Bynes (@AmandaBynes) March 22, 2013

Let that soak in.

Amanda has been exhibiting strange behavior since last year when she was charged in a couple of hit-and-run accidents, had her driver's license suspended, and fled Hollywood for NYC.

Drake has yet to respond to Amanda's offer, but he's not the violent type.

Unless you're Chris Brown.

Miley Cyrus sent a message to her fans -- and possibly her MIA fiancé Liam Hemsworth -- by showing her enormous engagement ring is back where it hasn't been for a while ... on her hand.

Miley posted a photo of herself -- in a unicorn onesie, by the way -- prominently featuring her left hand weighted down by her diamond rock.

As everyone's heard by now ... Miley and Liam have allegedly broken off their engagement. He's been with family in Australia -- and she's been spotted all over town sans ring.


After Miley was photographed (above) with her diamond bands, but NOT the engagement rock ... she hit up Twitter to explain it was being fixed at a jeweler.

Liam's still not back stateside, but now that the ring is back -- we gotta ask ...