Windows 95 build 40e

Windows Chicago build 40e is an early build of Windows 95 from early April or March 1993.

Microsoft Antitrust document PX01608 discusses issues with Visual C++ running on this build. Apparently, the Visual C++ 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 issues, this was because a standalone MS-DOS 7 release was to be released alongside Windows 95.

It is also worth mentioning that this build was apparently recompiled several times, which is usually only done with builds intended for a wider/public release. It is possible that this build or a later recompile was released outside Microsoft at some point in April or May 1993.