Can you provide steps to reproduce the problem?

edit: I added the actual error message to the HTML of the error page in an HTML comment. View source on the error page and look for:

    <!--
    Actual error:
    This is a test exception generated by SimpleErrorHandler 
    1.0.3764.33883. Please disregard.
    --> 

So, **provide me that**. I suspect this is XSRF stuff you guys are running afoul of, as we suppress all those "errors".. they're caused by networking problems 99% of the time.

edit: We did find a small bug that might have caused this in rare circumstances, for users who tend to switch IP addresses rapidly. Let us know if it's any better after today (May 14 '10).