This is great benchmarking application for PowerPC Macs capable of running Classic & Mac OS X. It may be a hardware compatibility issue. The application SpeedRun X is from 2004. As a direct result some Macs may be too new for it to work correctly. If you must benchmark Macs made after SpeedRun X's release date I would recommend using Xbench instead. The only downside is that Xbench can't benchmark Classic too.