It could be a number of things, what Operating System is he using? Some security programs will block Smitfraudfix and may need to be disabled. You can also try running Smitfraudfix.cmd from the folder that Smitfraudfix will have created when it was run.
Best to have him post a HijackThis log, though. Even if Smitfraudfix won't run, there are other tools that we can use to remove such infections.