Upon opening Isadora, the entire interface becomes unresponsive. No actors appear in scenes (as they are inactive and I cannot click into them), the cycles show 999.9, and the FPS 99.9. I previously bipassed this error by opening a 2.0 showfile, clicking "yes" on the conversion, then upon loading successfully, I went to file>open to access the desired showfile. The first time I encountered this, it was by surprise, but it stopped occurring after a day or two. I am now experiencing the same error a week later on an entirely different project.

Any ideas of what it could be?

Both systems had two graphics cards. Current system:
Asus Computer
1 ATI Radeon HD 2600 Pro
1 NVIDIA GeForce GTS 250
Windows 7 Ultimate
3 GB RAM
Intel Xenon CPU 3.17 GHz
64-bit OS