Debugger stuck

Hi,
I try to run the PC demo of FREERtos ver 6.0.5 with Open Watcom debugger.
I put break points on vTaskSuspend( NULL );  function call in prvHighPriorityMutexTask  task.
press ‘go’ and then ‘step over’ and get an error message of illegal instruction. Then, the debugger is stuck. I have to note that I encountered this problem with that debugger using break points in other places and depending on the time I step over a command, so maybe the problem is with the debugger? Any help will be appreciated Thanks.

Debugger stuck

The Open Watcom debugger allows interrupts to execute when you single step an instruction – even when you are in a critical section.  This can cause crashes.  Could that possible be the cause of your problem? Regards.

Debugger stuck

Thank you for your quick response. Does it mean that a context switch occur while I debug?
If so, how can I use the debugger ?

Debugger stuck

Except from the clock tick interrupt, what other interrupts can be used in the PC demo exec?
(I  closed the com test).