DAE Error 35 and crashing on "Open Session"

[NGL]

Here's another fun one...

2008 Core 2 Duo iMac, 2G ram. Audio on an Iomega 1TB Firewire drive. Snow Leopard 10.6.2 and official Snow Leopard PT patch 8.0.3.

During playback on a very light session (a few Xpand plugs) I will get a DAE 35 error during playback after a few minutes of work. Shortly afterwards, PT will probably crash.

Often (75% of the time) when I open PT and select "open session" I will get pinwheel of death / crash instead of getting the dialogue box to browse for the session I would like to open.

The most disturbing thing is that with both of these crashes, after I force quit PT it will quickly take down the rest of my system. If I try to do anything with any other open app (usually safari, text edit) they will each crash as well. Once I've force quite everything (including finder, as it will usually crash too) when I go to restart the computer, everything will disappear except my desktop picture, as if it's about to restart, and it'll stay there infinitely until I hold down the power button to shut it off.

So frustrated with trying to get Pro Tools to behave with Snow Leopard. Anyone get any ideas?

Thanks.

-Nick