This erros seems to happen randomly and in the whole system. Sometimes when we click in a button, or even try to login, a alert comes up with the "Message cannot be parsed" error.

Funny thing is that when I turn on fiddler, the thing stars to function ok.

Sniffing the connection via smsniff i was able to capture the traffic of the bugged and working postbacks. The contents were suposed to be rendered in a update panel.

It appears that the "bugged" response is the whole page again, what would cause such a thing?

Sorry about the undetailed question, my first here.

Regards