PageRequestManagerParseErrorException: The message received from the server could not be parsed.

Hi,

Here is a interesting situation. We have a ASP.Net 2 web site. We have used updatepanel and master pages. Everything works fine when we access this web site from local intranet and internet. Our company have two locations. From second location which is in VA if user tries to access and run the web site directly from internet everything works fine. No errors. If from second location user tries to access our website from VPN (Viretual Private Network) then the user starts getting "Sys.WebForms.PageRequestManagerParseErrorException: 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' "

Can anyone gives me an idea what is going on.

Thanks
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