Computer Freezes while loading Pro Tools

[GSG]

Hi,

I'm running a 2011 Mac Pro 8 core with an HD2 and PT9.0.2.

The system has run fine for around 4 months.

I opened it up last night and tried to boot Pro Tools - the grey screen with the "please restart your computer" thing happened twice, and Pro Tools never got past its loading screen. I went home.

This morning I switched on the computer, tried to open Pro Tools and the whole computer freezes on the "initialising hardware (DSI)" screen - that's the whole computer - mouse doesn't move, have to hold down the power button on the mac.

I've trashed databases and prefs. No difference.

I need to get this system going asap - please help!

C

- EDIT - Opening Digi-Core-Audio-Manager causes the same crash - Also worth noting that the crashes are moving between the grey screen 'of death' and straight freezes. I've unplugged everything connected to the computer, leaving only mouse+k/b, and DVI. I haven't yet removed the HD cards, but I will if no one has any suggestions.