Graphics Drivers gets unloaded on restart..?

My Screen resulation changes from 1280 by 800 to 1024 by 768 on evrey restart...and refresh rate from 60 herts to 58 herts....Dont know why i have formated my laptop and reinstall the win xp...its works proper for a 2-3 restart then it agains goes back ...after reinstalling the intel chipset driver and graphics driver its get okay...but again after restart the screen resulation changes.....So on every restart i have uninstall and install the intel chipset driver...but now this is also not working....fortunately i have created a Restore pount when the sysmtem was working fine....so now on evry restart i have to restore my system to that point....what can be the cause...??