There might be some kind of problems with the URL Rewriting in ASP.NET v2. CommunityServer is affected by this as you can see on this Screenshot:
This screenshot also shows you where to get this Tool – Fiddler ;).
First I made some tests with a site developed by us, we use custom URL Rewriting in the global.asax and everything runs fine, that’s why I’m not sure if this is really an ASP.NET v2 issue as it’s being claimed to be one by a couple of people.
Later on you see the CommunityServer Request and the possible bug: A 302 redirect instead of a 200 redirect which is very bad for SearchEngines. Due to this fact your site may drop out of most SearchEngines. Matt Cutts blogged on this, too: ASP.NET 2 + url rewriting considered harmful in some cases.
Anyone else got problems with a 302 Redirect when using URL Rewriting?
We are using Context.RewritePath to perform our URL Rewriting and didn’t run into any problems so far.