pcpitstop.com shows i have a virus of lsass.exe

i recently ran the full test on pcpitstop.com which i run occasionally to check my computers performance. it came up that i have the virus lsass.exe located in my my documents folder. i am unable to see it in there, even when i show hidden files and folders. it doesn't appear to be having any affect on my system. i recently downloaded something on limewire that ended up being a worm of some type that would start limewire and cause random pop-ups. i was able to stop all of that but it appears as is this is left over from that. i am wondering if anyone knows of any way to help get rid of this file and any possible infestations. ive ran the trend microhouse virus scan online and did ad-aware to remove anything in safe mode. any more ideas are greatly appreciated.