This is my first post to this community. I am having a severe problem with my system. I am running XP SP2, and have Norton Anitvirus Corporate on the machine. I may have inadvertantley let my guard down when trying to negotiate with XP over who was in charge of my computer. Anyway, I may have caught a virus. Perhaps sasser. At the present time I cannot boot my computer to the Windows desktop. During startup I progress to some point and get an error: Application Error: lsass.exe failed to complete...., and the system just goes to black screen.....dead. I have tried many things, and have gotten much advice, but to no avail. Tonight when I go home (I am writing this from work) I will attempt to reinstall the original version of XP. I tried to do SP2 last night, but the 266 megabyte program I brought home was "unrecognized" by the XP_SP2 SetUp/Repair program. I have done all manner of hardware checks, such as are available from the repair console command propmt. There does not appear to be a hardware problem. If this sounds familiar to anyone, I would greatly appreciate your thoughts.