PT MP locks regularly

[glessard]

in the last week or so my rig has started locking up more and more frequently. at first I thought this was happening during auto saves but now I'm not sure. I'll work for literally 3 minutes and then audio stops, the PT meters are frozen in place and a moment later the spinning balloon show up.

this is happening when I'm using any of 3 external HDDs, all glyph gt050q via FW800 / express card on my macbook pro. none of this hardware is new, I've used it all for a couple years without too many hitches.

I've deleted prefs, digi databases, repaired permissions, rebuilt disk directories using disk warrior, and would just like to get back to mixing.

any suggestions on how to diagnose this further?

MACBOOKPRO 2.33GHz 3 GB RAM
PT MP 7.4 CS
MAC OSX 10.4.11
M-AUDIO PROFIRE 2626 DRIVER V2.1.2-2 / FIRMWARE 1.0.10
PRESONUS DIGIMAX FS (ADAT)
GLYPH GT050Q (FW800) SEPARATE AC POWER
BELKIN FW800 EXPRESS CARD