Windows 3.1 build 058

Windows 3.1 build 058 is an unleaked build of Windows 3.1, mentioned in internal Microsoft e-mails from 1992-01, as well as 1991-12 , and a bug report from 1991-01-09.

The first e-mail states this build is a pre-beta build for Windows 3.1 Final Beta and was released to testers on 1991-11-26. The second e-mail describes an issue when upgrading from this build to build 061b (Final Beta candidate). Setup would always cause a general protection fault (GPF) after copying the file.

The bug report states this build displays the infamous "Non-fatal error" when installed on DR DOS 6.0, and that the problem continues in builds 060 and 061. This confirms that the AARD code was already present in this build.

Unconfirmed screenshot
There is also a single screenshot of this build, but it is unknown whether it's real or not.