Anything .exe won't work

Hi. My dad's computer was acting up so I tried to run some scans on it. I found that many things did not work, so I went to safe mode (he has windows xp) and ran a couple of scans with Malwarebytes. He had a trojan and on the second scan he had on called startmenu or something. I just figured it was a run of the mill virus and didn't write anything down like I usually do.

So, now I have tried to do all that I have been asked to here in these forums and I was unsuccessful in most all of it. Nothing works. My last scan with Malwarebytes said I was clean, but nothing .exe will work still.

Can someone help me with this?

 

Thanks a million TimW. That did the trick.