Windows 95/4.00.40e

Windows 95 build 40e is one of the earliest leaked builds of Microsoft Windows 95. It was mentioned in Microsoft Antitrust document PX01608 from early April 1993.

The document 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 (because a standalone DOS 7 release was planned, according to the developer).

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.