Trojan Win32.VB-FSX Detected with Avast! Sandisc U3 edition

Hi everyone,

I tried to access some files on my U3 Jump Drive this morning and when avast! U3 Edition finished it Host Comp. Scan it said that my computer had the Win32.VB-FSX Trojan and it was located in the lsass.exe file located in C:WINDOWS/Config/lsass. Please let me know if there is anything you've heard of that can remove it. I've used Spybot S&D, Ad-Aware PE, BitDefender Online Scan, and Windows Live One Care. Out of those ONLY BitDefender was able to find it. Is there any reason why only avast! U3 Edition and BitDefender would see it? BTW when I found it with both progy's they said they couldn't quarantine or remove it.

Thanks for your time,
xninaki