If you let someone use your computer and login to your account and if that
account has admin privileges then they can do whatever they want including
allowing malware to be installed. Have you done a thorough check for
malware? You should greate a separate limited user account for visitors to
use. Don't use the built in Guest account. Create an account with a name
like visitor and make a limited user account.
HOW TO Create and Configure User Accounts in Windows XP
http://support.microsoft.com/?id=279783
Malware Removal
http://www.elephantboycomputers.com/page2.html#Removing_Malware
THE PARASITE FIGHT
Finding, Removing & Protecting Yourself From Scumware
http://aumha.org/a/parasite.htm
Richard Harper’s Guide to Cleaning Pests
http://rgharper.mvps.org/cleanit.htm
After you know the system is clean look in task manager for what processes
are running, research what they are, then decide which ones you don't want
to turn.
First step to eliminate start up programs should be to check in the options
for the program you don't want to start and see if there is a setting to
tell it not to run at startup. The next step is to remove any entries you
don't want from the two startup folders:
C:\Documents and Settings\<username>\Start Menu\Programs\Startup
C:\Documents and Settings\All Users\Start Menu\Programs\Startup
For anything else uncheck their entries in the startup tab of msconfig:
Start | Run | Msconfig | Ok
Another option is to remove the reference to them from one of these keys in
the registry:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
Make sure you have a backup of the registry using a program like ERUNT
before making any changes to the registry.
ERUNT
http://www.larshederer.homepage.t-online.de/erunt/
http://www.larshederer.homepage.t-online.de/erunt/erunt.txt
Installing and Using ERUNT
http://www.silentrunners.org/sr_eruntuse.html
http://www.winxptutor.com/regback.htm