When, a few years back,  I had the chance to bring my location rig into the 21st century, after a bad start with some MOTU devices that were a fail, I bought a Macbook Pro, FF800, a few other things and the rig has been stable and reliable and easy for almost 3 years now. I've kept the MBP 3.1 on 10.4.11 for some preferred software that doesn't run past that OS.
This system has been seamlessly plug-and-play using BOOM RECORDER or Logic throughout that time,  hence my surprise Saturday afternoon when, in a check before taking it to a recording, the Macbook Pro simply refused to see the FF800. Tried everything I could think of for an hour and in the end, had to cancel the recording.

Any idea why this would act this way out of the blue?

JV