Can some one please help me.

I have two GoDaddy DNN installations. One works perfectly. The other is give me an error message whenever I click any OnPostback button within the DNN environment. The message is:

"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. ...."

I've searched the web for any help, but nobody has any useful suggestions. I cannot do simple things like change a password (the Manage Password button gives this error). What do I do to fix this? I am relatively new to DNN, and am trying to put a case to work as to why we should move to it, but this is starting to make we doubt my own argument. The first install was a bit tricky, but I got it working relatively seemlessly.

I've also gone down the avenue to re-installing DNN, altering my web.config file to match (mostly) the working web.config. Still nothing.

Thanks in advance

Paul