Hello, I have a server application that I am building using GHC 6.4 (yes, an update to 6.4.2 is on the horizon, but not in the immediate future - unless it fixes this problem :) ) under MSYS/MinGW. Things work pretty well, but under stress testing the app eventually throws a Windows memory access violation (c0000005) exception out of the exact same location in the regcomp function every time. When it occurs is not deterministic - it could be after 20 requests or 2000 (usually higher, though). Various Windows debuggers shows it as a memory read error. regcomp is called several times with each incoming request. I'm pretty sure it's not a multi-threading issue, as there is only one client sending requests over and over again. Can anyone suggest some ideas or debugging tips? TIA, Rich