Peter,
Couple of thoughts
1) You could try automating regular commands say every 5/10 mins of say
q pro,  q se,  q mo to confirm that there is nothing else going on during
expiration
2) If above confirms that there is no other activity during expiration, you
might also try automating the "show locks" command. This could be done either on
a timed basis as above, or by trapping the error message & using that to drive a
" show locks" . You could even do both.
This should at least confirm whether or not you have a real problem.

John



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