Answered my own question I had a problem with a jquery (jsonp) call to a WCF service that was throwing a json parsing error. Using ASP.NET 4.0 on the WCF side and jquery 1.7 on the client side. Turned out there was an old set of script tags on the page using language = VBSCRIPT. The browser was interpreting the returned json packet of script as "VBscript" instead of javascript. I placed a set of empty javascript tags at the top of the page and the browser is now interpreting the json as the proper javascript function. Hope this helps someone else. Tom