Can't start Rubymine

I've somehow managed to get my project into a state where I can't start rubymine. It's had the 'Updating index' dialog on the screen for about 30 minutes, has become unresponsive and is using all the CPU. If I kill it and start it again and the same happens.

Can I reset the project somehow to try and get it to start?

This is Rubymine 1.1.1 on MacOS 10.5.7

Thanks,

John