I'm debugging a source for a Mega32A. The CPU runs with 8MHz internal clock. The ICE3 is attached and the ICE clock is 1.99MHz. Sometimes it happens that a single step in AS6 does not return. My normal handling is:
press F11 (or F10) and wait for the cursor to skip.
If the problem occurs you wait for ages, a timeout window appears requesting to wait for another minute or to cancel waiting. Pressing the one or other button does not recover. Disconnecting the USB cable makes AS6 dialogues free, but any next debbuging command (Start,...) hangs again.
The only solution to recover to normal debugging is to power-off the target (which also removes power from the ICE 3).
PC: Win 7 -64,
AS: 6.0.1938 -SP 1