Windows Vista virus involving the error jit compiler

I am receiving pop up errors that state the following, "unable to load jit compiler (MSCORJIT.DLL) file may be missing or corrupt please check your set up or rerun set up" and then when i close that error i get SSPnotifier.exe config error and dsca.exe config error...please advise if this is a virus or trojan and if so how can i get rid of it...I am also trying to run my spyware software and it won't sweep. please help!! thanks