Using AJAX controls has lead to some problems that I'm unsure of how to fix. I'm using Mozilla Firefox 2, and these errors are popping up as dialogs.

My first problem is when I use an UpdatePanel and a Timer AJAX control. It updates every 20 seconds, refreshing the currently playing song for a radio. In the timer event, it changes a label's text in the UpdatePanel. After a while, every 20 seconds it stops properly updating the UpdatePanel and I'm getting endless popups giving me errors. It can be emulated by the timer posting back every  second and giving the time.
This same error can also occur when you stay at a page for a long time and then activate a postback.
The 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.
There are no weird calls and I haven't done anything different, so maybe assuming server trace is enabled? If that's the problem, how do I turn it off?

Another problem I've been getting is that when I 'back' to a page with my browser, and sometimes even after typing the address again, it tells me that "The state information is invalid for this page and might be corrupted." Is there a way to get rid of this?

Both of these problems occur in the Development Test Server and when I upload the pages to my hosted site with IIS 6.

Thanks to anyone who can solve either of my problems.
 - AirHead3.0