I need to append my comments with a very import observation I just made regarding the shared_ptr issue I am having. I just copied over the binary created on my SMP machine to my UP machine, and it is showing the same problem with releasing the underlying shared pointer resource. I had been compiling the full code on both machines (including the boost threading library dll), and comparing those results, and not actually comparing the results of the same binary. The two machines are: Dell Precision 450 Workstation Dual 2.4Ghz Xeon Processors Windows XP SP2 Visual Studio 2003 Intel 8.1.??? Home Build Single AMD Athlon-64 3200+ Windows XP SP2 Visual Studio 2003 Intel 8.1.025 I just realized I don't know the exact rev of Intel I have on my machine at work, but will check it in the morning. I know it is at least 8.1.019. I seem to be looking at a problem with either SMP vs. UP builds or minor revision changes in the Intel compiler. 8.1.025 being the known working version in this case. Also, I've gotten the same results with 1.32 and 1.33 RC2. Also, thanks for a great library. We have been using it pretty extensively throughout our app; including threading, shared_ptr, spirit, date_time, bind, filesystem and multi_index (there may even be more that I can't think of right now). boost has been great fun to work with. Cheers, tim