Pc Keeps Restarting Wont Let Me Install XP Etc

hey guys
have a weird problem with my desktop pc (emachine 420) it was working fine a few days ago then the next day it just randomly started restarting, i changed the option under startup and recovery (unticked box that restart on failure or something) and it made no difference....it restarts itself every few mins...i cant even just put a fresh install of xp on because it restarts half way through.

any ideas?

 

have you tried to go through F8 mode then safe mode

 

yeah i managed to get in safemode though it restarted itself before it loaded so i tried safemode with network and that worked but what am i meant to do now im in it?

the only thing i can think of as to why it keeps restarting is graphics conflict or something, the screen is a weird size and the graphic or video card is not found. i downloaded the driver and fixed that though so no idea why it keeps restarting every 2 mins