I don't know how I got into this situation, but a particular mutex semaphore persists between invocations of Rexx. (Actually, there are two of them now).
Running the statement at the end of this note as a standalone program shows that it can be opened without being created.
There is no other Rexx process running on my machine.
I'm "certain" that no non-Rexx process knows about the semaphore.
Rexx is not running as a service.
If I run the statement below before killing RxApi.exe, it returns "000001B8".
If I then use Task Manager to kill RxApi.exe and then run the statement, it returns "000001C0".
If I then run the statement again several time, it again says "000001B8" each time.
I'm running REXX-ooRexx_4.0.0(MT) 6.03 30 Jun 2009 in an up to date Vista.