Bug under VISTA, ableton 6.0.10
This tested on VISTA ULTIMATE upgraded to latest pathcs and with vista upgraded to sp1 beta 1
Just make this, open one track on ableton, pout to run, you can see the vumeter of move soft and smoth, now press "control + alt + delete" that call to the screen where you can call task manager etc etc etc, when the screen open for selt just press cancell.
Now look ableton vumeter, run slow, and bad.
Close ableton open again, and problem fixed, if you repeat you can see the visualitation of vumeters change to slow, and jerk movement.
I find other more complex way to create this bug situation, but this is the more simple way to make this happen.
Aparetly after this happen ableton us emore CPU........i apreciate if ableton team can confirm if this is a bug, hoppe this can be fixed on the next release.
Best regards