Hi, Thanks for your help in the past. I would normally drop the issue at this point until I get my build environment cleaned up (" My build is messed up, I haven't read the documentation. What is wrong with YOUR library?" LOL). but I do have one more question which I believe is related to boost regex processing. If someone has a known good regex test program or can point to an obvious problem it may be helpful. Again, this code seems to work with Microsoft's greta and boost gives identical results on a longer list of SIMPLER regexes so I reasonably believe that the problem is due to handling of more complicated expression ( One caveat, to be complete, is that greta did seem to return some spurious results but they are easily filter programmatically, things like negative location, but the plausible ones that I have checked manually are right). However, on this sequence of regexes (regexi?) I get either an abort OR the program hangs later on non-sensical execution (I know, "Gee, you have a build problem and the stack is messed up?"). myboost.cpp114 (GU.*?TACTAAC.{20,40}AG|^)(.*?)(GU.*?TACTAAC.{20,40}AG) myboost.cpp114 ATG(...)*?(TAG|TAA|TGA) myboost.cpp114 TATAA.*?ATAAA myboost.cpp114 (GU.*?TACTAAC.{20,40}AG|^)(.*?)(GU.*?TACTAAC.{20,40}AG) myboost.cpp114 ATG(...)*?(TAG|TAA|TGA) ( progam hangs in my code or had been core dumping in boost::regex ) I think I removed all the stuff with questionable support related to assertions as discussed before. Thanks. Mike Marchywka 586 Saint James Walk Marietta GA 30067-7165 404-788-1216 (C)<- leave message 989-348-4796 (P)<- emergency only marchywka@hotmail.com Note: Hotmail is blocking my mom's entire ISP claiming it is to reduce spam but probably to force users to use hotmail. Please DON'T assume I am ignoring you and try me on marchywka@yahoo.com if no reply here. Thanks. _________________________________________________________________ More photos; more messages; more whatever. Windows Live Hotmail - NOW with 5GB storage. http://imagine-windowslive.com/hotmail/?locale=en-us&ocid=TXT_TAGHM_migration_HM_mini_5G_0907