Man... have had this problem since I bought the keyboard 3 months ago.
I have a thread about this in the main forum (about Virus TI not working
with new Mac Pros... which isn't true... it's just this error).
I'm actually using Ableton as well. And I've had this problem on a Mac Pro,
Macbook Pro, and Athlon based XP machine.
Different levels of severity on each.
And it's really random... it will happen a LOT sometimes, then I'll go through a nice 4 hour run with everything working fine.
If the synth didn't sound so damn good for what I'm producing, I would have
sent it back

... but it's to badass to do so.
I AM going to try and get a replacement if this doesn't get fixed with the
latest update though.
Trey