Weird MIDI problem in PT8

[Worthing]

Hi guys, I'm on a Macbook Pro, OSX 10.6.4 and Pro Tools 8 cs3. In this case the hardware and software are not so relevant. I use a Yamaha MO-08 as my main MIDI device, connected through USB to the Macbook Pro.

My MIDI setup was working flawlessly until this week. Now it's all weird.

If I check MIDI setup in OSX (the same one you can access in PT8 from Setup>MIDI>Studio Setup or something like that), the test is correct, Yamaha sends the notes and the MIDI Setup receives them correctly too.

So the problem is somewhere in PT8. Here's the process:

- I create an instrument track, add any piano or synth plugin to it (tested this error with Ivory, Omnisphere, Mini Grand), select the track and also set it to "Record". The instrument track is routed to the regular Master track, no bussing or anything weird.

- When I play on the piano I hear no sound whatsoever, even though regularly this is all I would have to do to get sound. Also, the sound level bar on the instrument track doesn't show any action. It looks like it's not receiving the notes, and it's also not playing any sound.

- To my surprise, I tried recording even though I couldn't hear anything and could see no action, and the MIDI notes WERE recorded onto the instrument track. Then I hit play and the instrument track did play back the notes I had recorded. It is obviously quite unusable to record without hearing what I'm playing anyway.

- I also did the test with a regular MIDI track sending to a plugin inserted in an instrument track, exactly the same result.

- I reinstalled both PT8 and my MIDI driver in case there had been some corruption somewhere, but it didn't help.

Please remember that this setup was working flawlessly up until this week. Got any suggestions as to what I could try? Going crazy here!

Thank you very much