Computor problem??

Hi guys,
Seem to have a problem with our computor,I switched it on yesterday and put my password in and it turned itself off and went back to the main welcome enter password screen.Managed to get on it after a couple of times.
This morning it has done the same for about an hour,so when i finally got on i got rid of the main account and password for windows and did a system restore.Anybody got any ideas as to why this is happening?
Thanks

Morning,

It sounds as though you could have a virus, do a virus scan on your PC. If that doesn't reveal anything, (I presume you are using XP?) if so click on START>RUN>enter SFC and press enter, this will check all of windows system files for you.

Hope you get it sorted soon. Keep us informed.

Ian

Thanks,
I made some changes to my computor a couple of days ago and it's only done it since then,i've done a full virus and adware scan and nothing is showing so i've done a system restore and got rid of the main password.
Touch wood it seems ok now.
Thanks for the advice