Booting in Safe Mode (tap F8 key while booting then pick Safe Mode from the menu) and using System Restore to go back to a time before the problem would be the easiest option but if you have a malware problem then it won't be got rid of that way.
I agree with Uraiser
's advice about installing anti-spyware and running online scans but I'd recommend you start with Ewido - Ewido Anti-Malware
complements anti-virus software by specializing in detecting Trojans, Dialers and Spyware and lots of other stuff. It is free for private use.
Download it from here: Ewido download
When installing it untick
'Install Background Guard' and 'Install Scan via Context Menu'.
If you are not able to get internet access on that system you can update Ewido manually by transferring files downloaded to another PC -Manual update of Ewido:http://www.ewido.net/en/download/updates/
Signatures from the last 2-3 days ~200KB download.
Full signature database ~4.5MB download.
If you can get the PC on the internet here are links to scanner sites:Free online anti-trojan scans:
Online trojan scanner: http://www.windowsecurity.com/trojanscan/Free online Anti-Virus scans:
They do take some time to load and run and in some cases you can only use Internet Explorer, with ActiveX enabled, to access them but they are an excellent support for your existing anti-virus program.Panda Activescan
online - http://www.pandasoftware.com/products/activescan.htm
Internet Explorer only. Requires email address
. Requires Active-X components to be installed. Approx 12MB download.BitDefender
online scan - http://www.bitdefender.com/scan8/ie.html
Internet Explorer only. Must agree to a EULA. Requires Active-X control "Bitdefender OnlineScanner v8". Some of the options are not clearly explained.McAfee
online scan - http://www.pcpitstop.com/freescan/eTrust Antivirus
Requires "CA Web Scan Control" Active-X component installed.The "eTrust Antivrus Web Scanner" loads signatures, end of load indicated by display of drives under 'My Computer'.
Tick 'Cure' when the scan is completed.Trend Micro
Housecall - http://uk.trendmicro-europe.com/enterprise...call_launch.php
(European version, supports Netscape, Mozilla, Firefox and Opera
Link to 'Online Scan' at the top rhs of the page. Requires IE and Active-X components.
"does not scan RAM, boot sectors and MBRs, so it cannot detect malicious code located in these areas."Symantec Security Check
The virus scan "will not examine compressed files and will not fix files it finds to be infected."
The security check is somewhat alarmist.Avast
Only checks ONE file!F-Secure
Requires IE and installation of "online F-secure form" active-X component