We recently upgraded our software to 1.36. Still using Visual Studio 2003. Started getting these ! is_singular assertions. I think I have tracked it down to being NDEBUG. For example if my exe does not have NDEBUG defined and I call a dll that does then the assertion happens. I have found a little bit of information about it online http://www.nabble.com/Bug-in-iterator_range-when-NDEBUG-not-defined-but-boos t-asserts-are-enabled-td17161844.html This link has a proposed patch replacing #ifndef NDEBUG with #ifndef BOOST_DISABLE_ASSERTS in the range/iterator_range.hpp In limited testing this patch seems to fix the issue. I am wondering if this is a good fix or is it something more fundamental. Thanks, Bradley Russell Programmer NPC International (620)231-3390 x 122 ---------------------------------------------------------------------------- -------- NOTICE: This electronic mail message and any attached files are confidential. The information is exclusively for the use of the individual or entity intended as the recipient. If you are not the intended recipient, any use, copying, printing, reviewing, retention, disclosure, distribution or forwarding of the message or any attached file is not authorized and is strictly prohibited. If you have received this electronic mail message in error, please advise the sender by reply electronic mail immediately and permanently delete the original transmission, any attachments, and any copies of this message from your computer system.