I just posted this to another user who has the same problem so I'll just paste it for you.
Well that's one of the worst you can get. Sinowal infects a PC's Master
Boot Record (MBR), the first sector on a hard drive, where it's invisible to ordinary antivirus agents.It is the most advanced and stealthiest malware seen so far. None of the anti-virus software will remove it.
If your PC is infected, Sinowal removal tools developed by a few security vendors may be able to help you. The bad news is that even the best tool can't be 100% effective against a threat that's evolving as quickly as this li'l terror
I'm giving you links to anti-rootkit tool the first one is easy to use but isn't as good as the second one. Gmer the second is for experienced users read the documentation carefully Use AT your own risk. To be honest with you the only way you can be sure is to reinstall Windows.
http://www.download.com/Panda-Anti-Rootk...
http://www.gmer.net/index.php
Here I also found this it tells all about the infection you have and none of it is good news.
http://windowssecrets.com/2008/11/20/03-Dont-be-a-victim-of-Sinowal-the-super-Trojan