New MBox user-upgraded from AMIII-having problems

[Release]

What the hell is wrong here??!!!

Specs:
MBox, current firmware
PT LE 6.4/Corre Audio 6.5.1
G4 Dual 1GHz, 1.5 GHz RAM
1-80GB main drive (where PT and the OS is sitting), 1-40GB, secondary drive
All the audio is going through a mixer into the MBox, I usually record one track at a time.

I decided to upgrade to an MBox from an AMII/Toolbox and I might be regretting it unless someone can help. I searched the board for everything pertaining to an MBox problem, tried it all, and nothing works.

The blast of white noise. Out of nowhere, a searing blast of white noise. I figured out how to stop it by going into the playback engine and changing the CPU usage to another setting and this clears it up...for about 3 more minutes. It does it in PT, it does it in iTunes.....constantly. This is completely unacceptable.

If I try to save a file to my main drive, I get this error:
Could not save as "file name" because:
NeoAccess Error...
This worked fine with the AMII and I have no problems saving to the secondary drive.

One of the troubleshooting threads said I should unplug any USB hardware that I have. I haven't done this yet because what I have on USB is a Bass POD XT Pro, a MOTU Exress XT MIDI interface, the mouse and a ShuttlePro. There's no way I should have to remove THINGS I"LL BE USING WITH THE APPLICATION!!!

Pissed off? Yes I am. I needed to upgrade to either an MBox or a 002R because I need to keep the system upgraded. I work from home occasionally and I need to keep current and this includes PT. Everything was fine and dandy with the AMIII.

Any ideas? Core audio driver? Bad MBox? Anything?

[Release]

Anyone?

[Release]

I just tried it with Core Audio 6.4 to see if that was it. Nope. Same thing. Works for a few minutes then bursts into the white noise problem and only goes away if I change the playback engine percentage so it's not coreaudio 6.5.1.

Do I have a defective MBox or what's the trick? ProTools is completely unusable at this point (unless I want to get used to working at three minute intervals with the sound almost completely off to prevent my ears from being blown out).

Can anyone help?