I don't know what happened; this server has been very reliable but suddenly began having problems with a particular .NET 2.0 web site simply hanging - it wouldn't load at all. However, another ASP.NET site was still fine. Reinstalling the site didn't fix it, nor did deleting and re-creating the application within IIS.
Trying the event viewer was met with a horrifying "Microsoft Management Console has stopped working".
Some Googling led me to believe the .NET framework was the problem. I found a tool called the .NET cleanup tool - http://blogs.msdn.com/astebner/pages/8904493.aspx - which cleaned out .NET entirely. I reinstalled .NET 1.1 and 3.5 (which installed 2.0 and 3.0 as well). Using the .NET verification tool - http://blogs.msdn.com/astebner/pages/8999004.aspx - I believe these have all installed ok.
However, my server is in worse shape now. The Exchange 2010 Management Console crashes with an MMC error and now my other (previously reliable) .NET web app now hangs on loading too.
I thought I should use Computer Management to remove and re-add the application and web server roles but sure enough, MMC crashes.
If anyone can help I will be extremely grateful.
Thank you !