Could use some help guys. PLEASE! I just changed my headgasket and when after 5 min of having the car on it gives off a loud lock sound then turns off. I looked everywhere to see what the issue is and found the timing thrown way off according to the timing gears. The belt is less than 5 yrs old and has no cracks. I checked the tensioner. Good too. I checked everything I could to make sure it wouldn't have any issues. But after turning the car on again. It took less than 30 seconds before it happened again.
What could be causing this?! It's driving me crazy trying to figure this out. I went by the book on everything. Any info would be appreciated. I would like to have this thing up and running asap.

 

Is the belt slipping off? Are all your timing marks lined up? Did you put the metal ring back on the crank before you put the crank pulley back on?