I was compressing a project from FCP on a train and my battery went flat midway through.

When I plugged into power and reopened compressor, it would not work, quiting unexpectedly. It seems the project I was compressing has corrupted.

I have tried clearing history ( crashes again) resetting background processing ( does nothing)

Can someone please tell me how to delete history?

There are only 3 things I can think of for this situation:

1. Copy-paste your assets into a fresh project and re-output to compressor.

2. Use a pay-ware application to attempt to fix the project and it's associated files.

FCS Maintenance Pack - Maintain Final Cut Studio, Diagnose and Fix Problems, Manage Settings (http://www.digitalrebellion.com/fcs_maintenance.htm)

There was another free-ware application called FCP Rescue but that product seems to no longer be available.

3. Use DiskWarrior to fix any directory and or file corruptions caused by the power-failure.

Other than starting from scratch and rebuilding your project those are the only options I see you have.

Thanks Robert

This ended up working - History files are located in ~/Library/Application Support/Compressor/History.