If your computer is infected so bad with malware and viruses, that it cannot even start properly, then you should give F-Secure Rescue CD a try. The F-Secure Rescue CD is a free CD ISO image available from the makers of F-Secure antivirus and contains Knoppix (a derivative of Linux), an operating system that runs completely from the CD and allows access to your computer’s Windows operating system and hard disks.
You have to boot from the F-Secure Rescue CD and it will scan your computer for malware and viruses. Upon detection, it will rename all the malware files.
The first step is obviously to download the ISO file from http://www.f-secure.com/linux-weblog/files/f-secure-rescue-cd-3.11.23804.zip. Then you will have to burn the ISO image to a blank CD using a ISO image burner. You can find the following links useful :
Once the CD has been created, put it in the first optical drive of the infected computer and restart. The computer should boot from the CD rather than the hard disk. You would see a screen like shown. Just press Enter to boot into the Rescue CD.
If your computer has an active internet connection, the Rescue CD would start updating to the latest virus definitions. After the virus definitions update, it will show you a screen where you can select the partitions to scan. You can select all the hard disk partitions whether they are formatted with FAT or NTFS. You can also select the attached USB disks.
After selecting, just highlght the Start Scan and press Enter to start scanning. You can also just press S on your keyboard to start scanning for the malware and viruses.
Any malware files that are found are renamed automatically to the .virus file extension. After scanning is finished, you can choose to view the report. Th report will show which malware files were detected and renamed. Finally you have to restart the computer by choosing Restart Computer to by just pressing the R key on your computer.
The F-Secure Rescue CD comes with a manual in the PDF file format which describes all the details and step-by-step instructions on using the F-Secure Rescue CD. You can download the manual from here : http://www.f-secure.com/linux-weblog/files/rescue_cd_user_guide.20090717.pdf.