So, on our production machine, we started getting the error "cannot create the window" when most users start SQL Server Management Sudio (SQL 2012) and/or Visual Studio (VS2010).
Short version, Permissions to Machine.Config in C:\Windows\Microsoft.Net\
\Config were changed when we installed the AS400 OLEDB drivers (IBM System i Access for Windows V6R1M0), and almost nobody had rights to the file (the only person with effective permissions was me, apparently because I installed it)
I reinstalled .Net,.. No joy... Reinstalled the drivers... no joy... Then I did the most obvious thing I can think of - Give "Everyone" read access on the file itself (right-click, properties, security).
Lo and behold, it works.
