Log and Transfer for MXF files (Canon 300XF) suddenly doesn't work

I've searched for a solution and I've pulled out a few hairs...

We have 2 identical FCP7 MacPro workstations (2x2.66 dual-core Xeon, 16GB RAM, NVIDIA GeForce 7300GT, 256MB VRAM, OSX 10.6.8).

Both systems have successfully ingested MXF files captured by a Canon 300XF using Canon's XF plugin for FCP.

Until today.

One system doesn't ingest the footage anymore. One still does.

The faulty system sees the footage in Log and Transfer, but as we add the footage to the queue, the red exclaimation point pops up. Hovering over the alert gives us: ERROR: UNKNOWN.

Nothing has changed in either system.

Any ideas? Gremlins maybe?

Thanks!