choppy graphics (meters, counter) after a HW failure

[Rhinosaur]

I'm experiencing slow choppy graphics in PT HD 8, which had been working fine up until a particular event (which I'll explain in my next post).

Now when a session is playing, if I'm zoomed out far enough to see the whole song there seems to be no issue. As I zoom in (or out) the meters and counter slow right down, almost to a halt, until I'm done zooming - maybe that's normal? OK.

The main problem is once I've zoomed in, the meters and counter are no longer reliable... they seem to struggle to keep up. This is most evident on the click track, which becomes quite sporadic.

It's the same during either playback or record. I have window scrolling set to 'page'. It's not specific to any one session, and it occurs without any plugins in use (except click).

If I'm to zoom in even further to the point the wav becomes just an outline (I doubt I'd ever work like that during normal playback...) the scrolling jerks and then stops, and I have to zoom back out until the playback head is visible before it scrolls again.

There doesn't seem to be any other symptom - no audio glitches, error messages, or other sluggishness.

This was occurring on PT HD 8.0.3. After searching online I've tried disabling bluetooth, disabling airport, calibrating the monitor color profiles and using the defaults. I uninstalled Pro Tools (safe option, retaining plugins and settings), re-installed 8.0.3 and tested, then updated to 8.0.4 and tested, then to 8.0.4cs2 and tested, with no change.

The system:
OSX 10.5.8 Leopard
Late 2007 Mac Pro
dual-core Intel Xeon 2.66 (2 processors, 4 cores)
4GB RAM
separate SATA system and audio drives
GeForce 7300 GT with
1x Cinema HD 30" @ 2560x1600
1x Cinema HD 23" @ 1920x1200