That is: if you try to kill the first instance of PMSHELL (which initializes the PM environment), the system will lock up solid. This happens even if the first instance is a child of µDesk, and has been spawned by it.
The real problem is that PM has been written without thinking about the possibility of stopping it. Even on shutdown, the system is locked so that you can't do anything anymore, but PM is still there and functional.
So, if anyone knows anything more about PM internal structure, or knows a way to kill and restart it without locking the system, please let me know!!
Another approach that comes to mind would be a fast-reboot feature.
I remember a third-party DOS memory manager that had such a feature:
it did not reboot the whole system, but only made some sort of tweaking
to let DOS reload completely. I don't know how it was done, and don't know
if it is possible under a protected operating system like OS/2, but if
someone has ideas...