Vince Young's $1.69 Mil Mistake -- Failed to Repay 'Lockout Loan'

Vince Young is in trouble ... the struggling NFL star is on the hook for $1.69 million ... after failing to pay back a high risk, high interest "lockout loan" that he took out back when he was a member of the Tennessee Titans ... this according to court docs.

According to court docs obtained by TMZ, Vince went to Pro Player Funding in May 2011 -- during the middle of the NFL lockout -- and took out a loan for $1.876,876.88. PPF is a company which specialized in "lockout loans" for NFL guys looking to cover their bills during the pay freeze.

Young's loan was VERY high risk ... with high interest rates and a clause that allowed PPF to call in the entire amount due, plus interest, if Vince missed ONE payment.

And according to court docs, that's exactly what happened in May 2012 ... right after Young left the Philadelphia Eagles and signed a new deal with the Buffalo Bills, he missed his payment.

PPF instantly went to the court and obtained a judgment against Young ... ordering the NFL star to pay back the remaining balance on his loan ... plus interest ... totaling $1.69 million.

The number is close to the salary Vince will be making with the Bills this season -- he signed a 1-year deal worth $1.9 mil.

Young's situation is virtually identical to Baltimore Ravens lineman Bryant McKinnie ... who took out a $4 million loan with PPF on the eve of the 2011 NFL lockout ... and also didn't pay it back.

Bryant reportedly struck a settlement deal with PPF earlier this week ... agreeing to pay half of the $3.2 he's scheduled to make with the Ravens in 2012.

During the lockout, several NFL players spoke out against loans of this sort claiming they weren't in the best interest of the players ... and now Young and McKinnie seem to be living proof.

The loan drama is just the latest legal nightmare for Young ... the QB recently sued his former agent and financial advisor for allegedly cheating him out of $5.5 million Vince was supposed to have earned in his rookie contract and through endorsement deals.

10:02 AM PT -- Vince's rep tells TMZ ... Young blames his former financial advisor, Ronnie T. Peoples, for pushing him to take out the loan.