Thank God For Fiddler!!!!!!

OMG. Fidder saved me. I was getting the following error:
"Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed. Common causes for this error are when the response is modified by calls to Response.Write(), response filters, HttpModules, or server trace is enabled. Details: Error parsing near HTML dir='ltr'"
I started stripping everything out the page and even went to the point of creating a vanilla masterpage and the error still kept on popping up!!! Then I realized "Why is it still showing HTML dir='ltr'? I took that out three versions ago.". Let me use this handy tool called Fiddler to see what is being sent back to the browser. I opened up Fiddler and looked at what was coming back to the browser and the problem was it was trying to send an error message back to the browser but the parser had a problem parsing its own error message! The error message was buried in the response back. I fixed the error and that got rid of the cryptic Sys.WebForms.PageRequestManagerParserErrorException error.

Thank you Fiddler and whoever created it! I believe the guy works at Microsoft now.