Pro Audio Support

Q:
"Transport was stopped due to a problem with the external clock source" error during playback and record with Mbox 2 Pro.
 
A:

This error may occur if the Mbox 2 Pro is set to external sync, and the external clock is a sample rate that does not match the Pro Tools session sample rate.

Verify that the Sample Rate in Pro Tools matches that of your external clock.

In some cases, the error might persist after changing the clock settings. If this happens:
Quit Pro Tools
Power cycle the Mbox 2 Pro (disconnect the Firewire and Power cables)
Relaunch Pro Tools