A bug-fix release, fixing some annoying platform-specific bugs on Windows 2000 and Vista. You are recommended to upgrade to this release if you're running AxCrypt on Windows 2000, 2003, XP or Vista. This release is from the same code base as 1.6b4.3. See the release notes etc for details.
Don't forget to check out http://www.axantum.com/ for all about AxCrypt and Xecrets.