Need help with the removal of Desktop Defender 10

[Martingale]

Well this program has really got me, when I turn on my computer normally and log into my profile on the computer the only thing that comes up is this program asking for a cd key and a button to buy the full version of the software.  I can't do anything at all.  I can't close the program and when I minimize it there is only an empty black screen.  I can't open anything besides task manager.  And when i do that and try to end the virus's process (crss.exe) it says something to the effect of "access denied you don't have permission to end this process).  There is only one account on this computer and its the administrative account.  Any help would be hugely appreciated.
*edit if i boot windows in safe mode and end the crss.exe process I get the blue screen of death.  also i am using vista
*edit2.0 i got the computer to boot in safe mode ended the process desktop defender (though the program still gave me pop ups and stuff) than downloaded malware bytes ran a quick scan and removed all the infected files.  I restarted the computer ran a full scan and nothing came up.  Everything seems to be in order also it turns out that the crss.exe was the legit process and not a trojan one thats why when i ended the process it would give me the blue screen of death.

[rizeninme]

I am stuck with the same thing, except I don't know how to start the computer in safe mode, and Ctrl+Alt+Del won't work for me!!!! This is completely insane! Help!!!