Cannot load any OpenOffice apps

I have installed the full portable apps suite in the root of a 1Gb USB drive, and Firefox and Sunbird both work OK, but I get nothing at all from any of the OO apps. I have tried to monitor what happens via Process Explorer (from Sysinternals) but all I can see is that the process starts, then crashrep runs, then it all shuts down.

Does anyone have any idea what might be going wrong, or how I might diagnose the problem?

Thanks.