Our team has installed VS2010 on Friday afternoon. When I came into work on Monday morning, it appeared the installation of the .Net Framework (specifically the 2.0 part of it) was corrupted. Programs were complaining that they couldn't find 2.0 assemblies, and our main app was failing to start. Reflector wouldn't start because it couldn't find System.Data.
Trying to run the solution from the existing VS2008 version still on my machine was now failing as well. This was working perfectly fine on Friday, and I hadn't updated the code.
I searched through the event log and found that late Friday night, the machine automatically started installing hotfix KB979909, among others. This one stood out, though, because it failed to install. The hotfix description is:
MS10-041: Description of the security update for the.NET Framework 3.5 Service Pack 1 and for the.NET Framework 2.0 Service Pack 2 for Windows 2000, for Windows Server 2003, and for Windows XP: June 8, 2010
It seems that the installation has corrupted the 2.0 framework assemblies on the machine.
Since then, the update has been automatically applied on other developers' machines here, and they are now getting the same problem. I have no idea whether this hotfix was already on the machine before Friday night - it does seem a bit of a coincidence that the machine decides to install it very soon after installing VS2010, even though it would seem to have been just as applicable to my machine before installing VS2010.
I removed VS2008 and VS2010, and all versions of the framework to attempt to start from scratch. I then installed only VS2010. Now the machine thinks it doesn't have any versions of the Framework installed. VS2010 seems to still start ok. I tried to install framework 3.5 SP1 and the installer fails.
My investigations are ongoing, but I have found other mentions of this hotfix failing installation on the web, but not from a developer angle of "oh sh*t, I can't do any dev work, how do I fix this".
If anyone can help with this, I'll buy you a virtual beer. If you're in London, I might even buy you a real one.
edit: In response the the comment - this is on XP SP3 32 bit, on an Intel based system. Before installing VS2010, the machine had VS2008 SP1. No VS2005 or earlier versions.
Does anyone know of a log of hotfix installations? It may be interesting to find out if KB979909 had already been installed on the machine before VS2010 was installed (as the hotfix relates to 3.5 SP1 and 2.0 SP2).