If the debugger is not able to help you with locating a crash when executing the release mode version, map files should (see my post above to learn how these are to be used).

Map files are a standard way to locating the reason behind release-mode crashes, and an accurate way too - one I would recommend. If you are sure that the problem is with that TCHAR string usage, review the same and hopefully you'll fix it. BTW, map files can help you in being sure of this as the cause of the crash as well.