NIS 09 Neither Scan will start

Hi,

 

I thinking this may have something to do with either a virus or malware, but I try to start a Full or Quick Scan and they just hang and scan no files, then I can't even quit the program.

 

I've a Full Scan in Safe Mode but it doesn't find anything.  In normal mode I've had "a.exe" not working properly messages, which I've found out is a trojan and every 4 hours Backdoor.Tidservis blocked.

 

If somebody could help me clear this up would be much appreciated, hoping I don't have to take to drastic measures and format C:\