Paris Hilton -- No Brains, No Problem

Just because Paris Hilton didn't lock the front door of her home before it gotten broke into last week, that doesn't mean she still can't collect on insurance.

Two insurance companies tell TMZ if Hiltie had her jewelry insured for $2 million, leaving the front door unlocked wouldn't invalidate the policy. We're also told if the jewelry estimates are true, she's probably paying a premium in excess of $50,000 a year to insure them -- if she insured the jewels for the full amount.

We know cops have the suspect on video, but he's wearing a mask and a hooded sweatshirt.