Cannot capture, but can do pretty much everything else with deck. What now?

Question

Hello everybody,
I'm writing for the Gateway Media Center. We're basically a small group of students which handles anything video or TV related for a public school district, mainly the high school. Our main editing system (Mac connected to a MiniDV deck via FireWire)is the subject of this post.
And we've got a bit of a problem. I've seen it at least once before on these forums, but no solution in that topic helped.
Basically, we can't capture video or audio with Final Cut Pro, but we can control the deck, watch audio levels coming from the deck within Final Cut, and even record edited material to tape with the deck just fine. We CAN capture with another application.
I'd like to say that NO, we have not updated anything within the past six months or so, at least not to my knowledge. (The problem started last week).
*_A detailed decription of what DOESN'T work:_*
Log & Capture window: The preview monitor within the window always shows the default color bars and the black horizontal band that roughly says 'Preview Disabled'.
*With device 'FireWire NTSC' selected:*
*Aud+Vid, Capture Now:* The black window with the whire Final Cut window opens. The bottom says 'Waiting for Timecode'. After this sits there for a few seconds, a message pops up and says roughly 'The operation could not be completed because there is no video'. The deck is automatically paused.
*Video Only, Cap. Now:* same as above^.
*Audio Only, Cap. Now:* Black window, bottom says 'capturing now', as it should, but when the Esc key is hit a message that says roughly 'ERROR: Final Cut could not read the movie file just captured' pops up.
*With 'Non-Controlable device' selected:* same as above, except that 'Waiting for Timecode' is replaced with 'Allocating Disk Space'.
*A detailed description of what DOES work:*
- Video and Audio go TO the deck, whether it's from Timeline/Canvas, Viewer, or Print to Video. I succesfully recorded an edit to tape just yesterday.
- The deck can be controlled with the JKL keys, the buttons on the Log & Cap. window, go to In point and even Batch Capture cues the tape correctly.
- Timecode is visible in the top right of the preview monitor in the L&C window, and it is the right timecode.
- Audio levels visible (in that stand-alone window which is usually to the right of the timeline) match what I'm hearing from the deck's analog monitor.
- Vidi, a simple little program, can record video which is manually cued with the deck. The saved video file(s) can then be successfully imported into FCP.
_*Trouble-shooting ALREADY attempted:*_
1) Correct turn on order: Shut everything down, unplug the deck's power, turn on and log into Mac, plug in deck and wait for it to wake up, turn the deck on, then launch Final Cut.
2) Check deck's input and output settings.
3) Unplug other FireWire devices. (We use an external hard drive connected on the same firewire bus. Not that it's ever been a problem)
4) Change Captrue Scratch location and make sure there's enough disk space.
5) Delete Final Cut Pro Preferences and that 'com.apple.finalcutpro.plist' thing.
_*Trouble-shooting NOT attempted:*_
1) Replace FireWire cable. I think it's safe to say the cable's fine since the computer can capture with Vidi, but I guess I should try this too, next time I get a chance.
2) Remove receipts and Re-install Final Cut Pro. (Really, a last resort.)
_*The specs:*_
Yes, this stuff is pretty old. Like I said, we're talking about a pulic school district, and the system usually suits us just fine.
FCP: Final Cut Pro HD (Academic) 4.5
+set up with the 'DV NTSC 48kHz' Easy Setup. Video playback on 'FireWire NTSC 720x480'. Yes, External Video All Frames.+
*The Mac:* PowerMac G4 (of what I believe would be called the MDD case model family)
OS: Mac OS X, version 10.3.9
CPUs: Dual 1.25GHz PowerPC G4, 2 MB L3 cache per processor
RAM: 1 GB DDR SDRAM
HDDs: Two drives, reportedly on the 'ATA-6' bus.
*The Deck:* JVC SR-DVM700 (3-in-1 MiniDV (with the 'PROFESSIONAL DV' logo), hard drive, and DVD-RW/RAM), 4-pin FireWire port connected to 6-pin port on Mac.
+Deck's Monitor:+ one professional CRT video monitor with built-in mono speaker, analog inputs directly connected to deck, made by JVC.
Sorry about the long post, I wanted to make it clear.
We're getting into a nice crunch as the school year is ending, and we really need to get this running. Any tips would be great!
Thanks,
Jake T.
+Gateway Media Communication Center / Gateway High School Video Club / Gateway Video Productions+

Answer 1

That makes sense, but our problem started last week - Final Cut captured fine before then.
And I don't think it's been updated lately, as 7.4.5 is the latest version of QuickTime for OS10.3.9. If an update caused the problem, wouldn't the update be to 7.4.5, and not 7.3.1?
Nevertheless, I'll try it.
Thanks,
Jake T.