Pro Tools Crashes without notice..

[trelobas]

everything seems to work fine up to the point I open the workspace window and click on the little speaker icon to preview a sample/loop. Click and Crash , the program just disappears. any suggestions? the samples I'm trying to acces are on an external firewire drive. I tried trashing preferences and digidesign database folders from all mounted drives I also (once again) repaired disc permissions on the OS X volume. still no progress.
The rig consists of a dual 1 Ghz g4 Mac 1.5 Gb Ram running OS 10.2.8, HD2, 2 192's with A/D and D/A expansion boards, a Glyph scsi rack w/ 2 trays. Also installed are Waves Platinum, McDsp(all except the amp and the synth), Studio Bundle from Native Instruments, Bomb Factory Complete, Eventide bundle, Massive pack 2 bundle, Antares bundle, several digidesign Plugs , Trilogy and amplitube and Steinberg's Nuendo v2.10.1. I'd appreciate any suggestions from other usres and Digi admins.

thanks
D.