I have a Windows XP VM on my computer that runs my client connection to a piece of essential hospital software. It cannot be run on a machine that has .NET 3.5.1 and > 4.0 installed simultaneously, or it throws assembly compatibility errors. The ActiveX components seemingly only work in IE8, not even IE9 in compatibility mode. The vendor will probably only fix this compatibility problem when the piece of software has even less support than VB6 (i.e., virtually none). Because healthcare.