I have a Sidecar with a hard-card (being used as JH0:), so I will try to
recreate your problem sometime this week. If it happens (which I expect),
it is probably caused by MS-DOS being a non-multi-tasking non-reentrant OS.
From what I have heard, it can't even handle simultaneous disk I/Os.
I can't say that I have noticed any additional use of memory by DJMount.
Have you changed the number of buffers for JH0:?
BobS