have you tried a different instrument on the DI? that might be an obvious response but most of the time the obvious thing is the thing i do LAST.

Sounds like your gain is too high on the M-Box. If you mute the channel, then press record ready you wouldn't get the blast of static. Try recording that way. If the signal is severely clipped, then you know the gain is to high. If it sounds OK, just lots of static and distant sounding, then check that you have the correct input selected on the channel you are recording.

Sometimes, it's just bad communication between the computer and the interface. Somewhere along the line, a 1 became a 0 and things go wacky.
Sometimes, just closing and reopening the song works.
Sometimes, you have to restart PT.
and then there's times when you have to shut down the computer. (Full shut down then restart. Don't just hit the restart button)
If that works, then all is well. If the problem persists, then it's something else.

I've tried all of the above and nothing is working :S

even if there is no instrument plugged in, and i press record-ready, it still makes this horrible noise. and if i turn the gain all the way down, it is still full blast. i've tried restarting pro tools, and restarting the computer and nothing does the trick.

Any other suggestions??
:?

Turn your speakers down?

Perhaps the MBox is going kaput. Is there an easy way to get it serviced, or can you source another MBox to check with?

you might to uninstall PT and do a clean Reisntall. DOn't worry- it won't delete the pro tools session files. but you might wanna back em up anyway.