This is sort of a final report to thank the list for several good pieces of advice. I'm just completing a project which uses boost libraries to assist a project which uses shared memory to communicate between a 64 bit process and a separate 32 bit Application. Trying to use the managed version of shared memory proved to be too unreliable. Doing so is advertized as "experimental" and it proved not ready for prime time. I succeeded by using only the very simplest, unmanaged versions of boost shared memory and managing my own memory, very carefully, to be sure the shared structures were identical on the 32 and 64 bit sides of the divide.