I cannot boot up my desktop. Every time I try I receive the following:

lsass.exe application error instruction at 0x0040182 referenced memory at 0x00000000 the memory could not be "written". When I click debug all I get is a black screen and nothing else happens. Please help.

Anna, perhaps you would check what I wrote in this post: http://www.daniweb.com/forums/thread162461.html
Good luck, and please come back with what you find.