Windows 95 build 40e

Windows Chicago build 40e is an early build of Windows 95, mentioned in internal Microsoft e-mails from early 1993-04.

The e-mails discuss issues with Visual C++ running on this build. Apparently, the Visual C++ development team had access to at least part of Windows 3.1 source code and used an undocumented private function in Shell VxD to create their virtual machines. Under Windows 3.1x this worked fine, but on Chicago build 40e it doesn't because the Windows-specific shell services were moved into a separate VxD named WShell. According to the developer describing the issue, this was done because a standalone MS-DOS 7.0 release was originally planned to be released alongside Windows 95, and those plans persisted well into 1993.

It's also worth mentioning this build was apparently recompiled several times, as indicated by the letter "e" next to the build number.