There are a number of things you could try, I would have suggested you try Unlocker but that seems not to work.
Presumably you are running the OS with full Administrators rights. In which case you could right click on the files and remove any protection and then try to delete them.
If you know which program the files belong to, you could use Task Manager to end it and then try. If that fails try Autoruns click here and stop the program running at startup or go to Start>Run and type `msconfig` and stop it from there.
You could also try starting in `Safe Mode` and see if that helps.
If these fail to work then it looks as if there is a Registry entry that needs modifying - this is beyond me.