G4 17' Powerbook 1Ghz 100GB HD. I was working in FCP5 and went to export using Compressor and then when I went to submit batch, I received that error message.
I couldnt find anything in the archieves here and looking around the net I saw a couple of solutions, none that worked. I reinstalled software (Production Suite) trashed FCP pref. have enough memory where I am storing this media. Disk disk utility, Tech Tools and Disk Warrior. No help.
Check the Final Cut Pro forums on the Cow. This issue comes up often over there (look in the archives as well). I have only experienced this with Compressor 1.2, a long time ago, and the 1.2.1 update fixed it. Also, an update for Compressor 2 was just released just yesterday, so see if that helps.