I'm running Sitecore 6.1 on Windows 2008, IIS7, and I'm trying to use the URL Rewrite Module to do a redirect. When I enable the rule and hit the URL that triggers it, I get a YSOD. The same rule works perfectly on a non-sitecore site on the same machine. According to the Failed Request Trace, the rewrite module does its thing just fine, but then Sitecore throws an exception, even if the redirect points to another server. This is probably a result of something I have misconfigured, but I just can't understand why it doesn't work. The details from the YSOD are below.
[NullReferenceException: Object reference not set to an instance of an object.]
Sitecore.Nexus.Web.HttpModule.(Object sender, EventArgs e) +273
System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +68
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75