...Snipped...

No. This problem started occurring when I integrated the whole system 
together. I'm going to have to work on it a bit to reduce it to a 
suitable code segment .
The Xenomai content of the loop is:
while (!end) {
     ...
     rc = rt_event_wait(&event1,..);
     ...
     rc = rt_event_clear(&event1,..);
     ...
     rc = rt_event_wait(&event2,..);
     ...
     rc = rt_event_clear(&event2,..);
     ...
     rc = rt_event_wait(&event3, TM_NONBLOC, ...);
     if (rc==0) end = 1;
}

Is this is a loop using all the CPU (all the events with TM_NONBLOCK) ?

• The above calls are in a rt-user-task and are bracketed with bind/unbind, outside the loop. The task starts in secondary mode, performs the loop in primary mode, then finishes in secondary mode.
  
• rt_event_create and rt_event_delete occur in a rtdm driver init and exit routines.
• However, rt_event_signal is invoked in interrupt handlers. I think that this may be unusual. Normally, interrupt handlers would use the rtdm_event mechanism.