HijackThis
HijackThis™ is a free tool which scans your computer to find settings that may have been changed by spyware, malware or other unwanted programs. HijackThis creates a report, or log file, with the results of the scan. HijackThis doesn't use a database of known viruses, but simply presents a list of the software present on your computer that employs virus-like behavior.
Once you have downloaded HijackThis, execute it and run a scan. It will create a log file while will enable you to find out if your computer is infected with spyware or viruses.
If you need more assistance, post your HijackThis log at Spyware/malware related forums like www.spywarewarrior.com and they will assist you in cleaning your computer.