Potentially Dangerous Request.Path (:)

I just updated our website to .NET 4.0 and ever since then I'm getting the following exception.

"A potentially dangerous Request.Path value was detected from the client (:)."

The requ开发者_如何学Pythonest URL is: "https://OURDOMAIN:443/:/0"

This request is from many different IPs but the client app seems to always be IE 6.0-8.0.

Why do we keep getting requests for ":/0" and how can we stop this filling our event logs?

Update:

It turns out it was a bad javascript file that was creating the erroneous request. Now I just need to figure out what's going awry in the js file.

The request has to be coming from somewhere.

Do you have an invalid link on your page pointing to it?
Maybe check your Routes in the Global.asax.cs file.