Mac OS 10.5.5 or QT 7.5.5 breaks P2 ingestion w/log & transfer

Question

The title says it all.
I just upgraded a Mac Pro 2.8 dual quad-core with Mac OS 10.5.5 and QT 7.5.5. Everything worked spiffy before. Having been around the block several times, I performed all the usual routine maintenance stuff before the upgrade -- repairing permissions, etc.
Now, the machine will not ingest P2 media using the Log & Transfer function on FCS 6.0.4. I can still view, select, trim, rename -- but I can't ingest the clips. When one adds the selections to the queue, the program starts the process. The status window in the log & transfer function shows a spinning wheel as normal, but when the process is finished, the wheel freezes. An exclamation point then pops up. It's like the program has captured it, but then doesn't "build the file." FCS is not completing the process, in any case.
I wish Apple's left hand would tell the right one what it's doing!

Answer 1

We updated to 10.5.5 for security reasons and bugfixes, not so much because of a "compelling workflow change." In our opinion, 10.5 really wasn't ready at all for "prime time" when it was first released. Maybe we didn't have to upgrade to QT 7.5.5; but over the years we've found that QT upgrades tend to be more stable when system software point upgrades are done at the same time.
To answer your other question -- we don't tend to do complete HD backups, simply because they're a PITA. Sure, we've got the external drives to do it; we just don't have the time in many instances. I'm not saying we never do them.
Our digital video experience goes back to the Mac IIfx, the bad old days of Truevision Targa boards, and Premiere 1.0, so we tend to rely on our brains and our wits to get out of hardware and software issues. In this case, we still had the P2 clips, and if needed, could have ingested them on a different machine (fortunately we were not on a time-critical deadline). Call it hubris if you like, but our approach to troubleshooting works okay for us.
In our shop we have several machines to shoulder the work, and can afford to use one to test things before upgrading the lot of them. This was the case in this instance.