keygen.exe is installed and used by NetOp Remote Control 7.5 parasite. This process silently works in background and performs harmful actions, which is why keygen.exe should be killed and its parent file removed from the system.
If you cannot erase it, consider using recommended spyware removers, which will get rid of keygen.exe and associated parasites for you.
If your computer seems sluggish, or you are suffering from unwanted advertisements and redirects to unknown websites, we highly recommend you to scan it with reputable anti-spyware program. Do some FREE scan tests and check the system for unwanted applications that might be responsible for these problems.