System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.FormatException: Invalid character

I started receiving these errors a couple of weeks ago, very randomly, and always reporting a fault with ScriptResource.axd and a strange parameter being passed as "d" as a querystring to it.

After some reading around, I eventually came across the following thread that was dicussing the issue.

https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=434997

The end of the thread, dated 12/10/09 states that this is a bug in IE8 that is hopefully going to be fixed soon, and that it doesn't affect the end users view of the site.