My systme keeps crashing so i started up the my system with the dell diagnostic CD.  I ran the harddrive test and i get the error code 0F00:075D.  I thought it might have been the OS been corrupted so i poped in the reinstall disk and ran CHKDSK /f.  I think it fixed the problem so i restart my computer and starts up fine and i run a health and system health report and it said the harddrive was fine.  I go online and doin somethings and suddenly the browser crashes, i do a control alt delete and the screen turns black and an error pops up and says something about "system login security falure" or something like that.  and i have to restart. So i run th ediagnostic test again and it says that same errorcode keeps coming up. How do i fix this?