[beepbleep]

I have performed a downgrade of Lion to Snow Leopard and updated this to 10.6.8. I installed the latest drivers for MBox - Mac Releases v1.0.21 (Aug 17, 2011) and all I get is a almost inaudible but annoying high pitch intermittent buzz through the monitor or headphone output of the MBox. This gets more busy when I try to play a tune through itunes. This gave me very little confidence that pro tools would work!

I downgraded to a clean install of Snow Leopard from Lion because I had the same problem and thought it might be due to OS incompatibility.

From both Lion and Snow Leopard, after I installed Pro Tools Express (10.2.0) the transport (play) button simple produces an error message:
CPU usage is holding off USB audio. Remove some plug-ins, delete some tracks, or increase the "H/W Buffer Size" in Playback Engine dialogue. (-6104). I tried the suggested change to the playback engine (just for fun?) but no change.
I have not been able to record /register or play a single audio sound of any description from Mbox or pro tools?

My SetUp is
iMac (Late 2006) and 233 GHz Intel Core 2 Duo
OS version 10.6.8
AVID MBOX Pro Tools Express
3GB RAM installed
Attached peripherals:
From the USB High-Speed Bus (back of computer):
Mbox and 3TB Seagate Expansions External USB Drive (not used for anything related to protools and problem also exists when this is not attached
(I was going to use this as an internal drive to replace the small/old original internal drive). The internal drive is to be used for recording and playback although I will get a Firewire external drive later. On the Hub in the Apple Pro Keyboard I have the iLok (new version) attached (I think this is USB1 not USB2)

Yes I have made Required and Optional Optimizations according to the Snow Leopard Computer Optimization and Troubleshooting Guide
In addition I carried out the first step in Trouble Shooting RE: Not Hearing Input or Output, but that made no difference.

I seems to me the MBox drivers are simply not working so everything else is superfluous? I have since read on one of the many many disparate pages on the AVID site (though I cannot find it again???) that my machine may not be supported?

Here the bit where I cry for Heeeeellllppppp????