System Restore has a nasty habit of not working and I can't guarantee to offer any way of getting it to do so.
However it's always best to disable everything that's running 'in the background' before trying to use System Restore. The easiest way to do that is to restart your PC and to press F8 while the computer is going through the boot process. That will take it into Safe Mode. Your screen will look odd (because the video driver won't have loaded) but you can still get to System Restore, which might now run.