Try running your two programs at the same time. Due to the fact that you are unlocking immediately after locking (my previous post #1), if you start the two programs at the same time you do not have issues, because the 2nd program completes before the 1st. The 2nd program will crash only if he tries to access the mutex after the 1st program completes, because you destroy the mutex at the end of program 1. Since program 1 creates the mutex, it must start before program 2. Due to the fact that your program 2 is supposed to end after (from what I see), I would suggest moving seg->destroy<SharedMemData>("TrackOutput"); to the end of the 2nd program. Mind thought that you also need to correct the issue with locking I mentioned in #1 of my previous post, or now it will be program 1 the one crashing. -- View this message in context: http://boost.2283326.n4.nabble.com/interprocess-Interprocess-mutex-not-worki... Sent from the Boost - Users mailing list archive at Nabble.com.