No one but you can answer if you have a virus. You've posted quite a lot
lately about problems you've been having but have never answered the
question as to whether you've scanned for malware. Certainly malware can
cause the symptoms you're seeing but we simply don't have enough
information about your system and its recent history to give you focused
help.
You can try and logon with a different administrative account. If you don't
have one (and now you know why having an extra administrative account is A
Good Thing), then you can enable the built-in Administrator account and
assign it a blank password with NTpasswd.
http://home.eunet.no/~pnordahl/ntpasswd/
Once in, you can scan for malware and also see if you can find out what is
wrong.
http://www.elephantboycomputers.com/page2.html#Removing_Malware
If you're unable to do this yourself, take the machine to a qualified
computer tech. I don't recommend using a BigComputerStore/GeekSquad type of
place.
Malke