BleepingComputer.com: User account & System restore issues

I run XP Pro. After having several issues with the computer rebooting (I think it's fixed), I found a new Administrator user folder that was created somehow. I've compared the creation dates of MY user account and this other Administrator folder. This new user folder WAS called Administrator.OFFICE.000 (I deleted the old Administrator user folder and renamed the office.000 to plain Administrator). My computer's name is OFFICE. The date stamp that it was created is: Nov. 5 at 6:47 am. MY user account was created on Oct. 26 at 9:04 am. I looked in the Office.000 folder and it is 1.57 MB in size. It contains desktop, favorites, my documents, start menu folders (the normal view ones). The hidden folders are: Application data, Local Settings, Nethood, Printhood, Recent, Sendto, and Templates. It also has two files at the root of the office folder: NTUSER.dat and NTUSER.vcd.

Here's another issue. I have two user accounts on my computer besides the Administrator account: Samual and Sonda (my gf's account is a limited one). When I use the WINDOWS key + L (to lock the computer or switch user), either account gets asked for a password. There is no password set on either of those accounts. I have checked it multiple times.

I have tried to use System Restore to revert back, say to when I did the fresh install of XP. BUT, each one fails. System Restore is not working at all. Due to the constant failures of System Restore, I simply turned it off.

Any advice?

Btw, if anyone needs the info about what has been done, the link is: Virus causing computer to reboot.