desktop.exe spyware making me nuts

I do some side computer work for people and a few of them had this spyware known as desktop.exe. I have tried many times to remove it from the startup using msconfig but it always starts again. It denies me access when I tried to delete it using explorer. I cant even delete the registry keys when Im logged on as administrator. I ran the microsoft anti spyware and spybot and it will not delete it . does anyone have any advice how to get rid of this spyware?