Introduction to the three designer handbags(Chanel,Coach,Prada)

Due to an interrupted ontape restore, I was left with a down informixserver with its shared memory segments still being reported by ipcs. I carefully removed all the segments using ipcrm, being careful not to remove any used by the other two instances on the host, but when I removed a semaphore segment from the fouled instance, the other two abruptly crashed with "Assert Failed: semop: errno = 36" messages appearing in the Informix message logs for each. Has anybody else experienced this? I can find no mention of this behavior in Informix manuals, online, etc. I assume that in some way the other instances are using that segment of memory. Using IDS 11.50.FC4 on HPUX 11.23 (memory management with this O/S has always seemed problematic).