Help i need a techy

it's a weird problem but when i tried to start the game it restarts my computer now i have tried install and reinstall, and repair doesn't work, the problem it started when i was first playing it and i forgot to log out and my Dad was making a backup and well when i went on the next morning while it was doing backup tryed to play the game and it gives me that im right now on a temporal user account and i should restart the computer ask my dad to restart he says yes a restart the computer and boom this happens and tried to play this great game it reboots and it reboots after the anti-cheat system does it's check and then reboots my comp. the computer now i was chating with a player on Xfire about this problem and he says to reformat my comp. but don't know how to do that are there any other opinion or do i have to do that

i have a win 7 laptop
maker: Lenovo
Model: G550
type of Windows: win. 7 home premium
internet: Fire fox
RAM 4 GB
HD space (30 when not installed 25 when installed)


P.S (my birthday was 2 days ago im 17 now =)