(If you have Win XP, turn System Restore off. Click Start, right-click My Computer, and then click Properties.
In the System Properties dialog box, click the System Restore tab.
Click to select the Turn off System Restore check box. Or, click to select the Turn off System Restore on all drives check box. Click OK.
Click Yes to confirm that you want to turn off System Restore.)
Download, install, update and run full scans, in SAFE MODE*, with these programs...
http://www.malwarebytes.org
http://www.superantispyware.com
http://download.cnet.com/1770-20_4-0.html?query=Ad+Aware+Free+Anti+Malware&tag=404&searchtype=downloads Ad-Aware free
*** Important, when downloaded/updated disconnect from the internet ***
Then re-start.
(turn System Restore on. Click Start, right-click My Computer, and then click Properties.
In the System Properties dialog box, click the System Restore tab.
Click to clear the Turn off System Restore check box. Or, click the Turn on System Restore on all drives check box.
Click OK.)
If you can't run a scan, go into the scanner's folder and re-name the .exe file to something like 'MyFile.exe' and try in safe mode again. Some malware prevent the execution of anti spy/mal/virus scans by blocking them by name.
You should consider getting a good Anti-Virus program.
Try one of these free ones...
http://www.avast.com/eng/download-avast-home.html
http://www.free-av.com/en/download/1/avira_antivir_personal__free_antivirus.html (Avria)
http://free.avg.com/download
***Never use more than one anti-virus program at any one time***
*Note: On start up (before Windows loads) keep tapping either F5 or F8 (be aware that some manufacturers use F8 for system recovery!) then use arrow keys to highlight 'Safe Mode with networking' and hit Enter/Return, click on a user account, enter the password (if you don't know it, there probably isn't one so leave it blank) and hit Enter/Return.