Track down Pwsteal.trojan

Virus is just like a tumor. When you have one, you're likely to make any effort to get rid of it. However, it's not an easy job; in fact, it is very demanding. I've been trying to delete a virus file- htdll.dll for two days, wasting a lot of valuable time and sacrificing my sleep, and every time it seemed that i'd completely remove it, but that damned "htdll" reborn and appear at the same location again right after rebooting the computer.
I've checked this problem on the net, and have done all the tricks like rebooting computer in "safe mood" or "Dos", deleting all the suspects from "registry" or renaming the file, even followed the step-by-step instructions according to the suggestion of anti-virus company like symantec. All i got is another disappointment.
Above all, to track down and stop this slippery virus, I have to get to the bottom of this and find the main culprit behind the scene. Otherwise, the ultimate measure will be this-format the system!
(I've spent too much effort on this meaningless stuff. I've got to do something interesting instead- today is my dayoff.)