HELP! Computer freezes then says "Failure - Security Options"



My new computer runs nearly perfectly on games like crysis (even in high graphics w/ 1680x1050 and no AA) then out of nowhere it just freezes. if I let it sit for a moment it goes to a black screen and says "Failure - Security options. Login process has failed to create the security options dialog." HELP! I just want to be able to play my computer games... :(

My Specs

700W Rocketfish 12V ATX PSU
Phenom II X4 940 3.0Ghz w/ Thermaltake SpinQ heatsink
Crossfire 2 XFX ATI HD4850
ASrock A780GXE/128M
8.00GB Corsair DDR2 800
1TB WD Caviar Black 7200rpm 32mb Cache
Windows Vista Home Premium 64bit

all the lastest updates for everything have been applied.