Error in Mail
There is an error synchronizing your mail account. Please verify your account has been configured correctly by first accessing your mail on the web.
Error: 4102. Client. Cannot change immutable data: MessageClass.
If you use the Outlook connector for your MSN or Hotmail account you may have started to receive this error (and the fact that you have no new email). Microsoft is aware of the issue and a fix will be available soon.
10/31/2007 UPDATE:: This issue has been resolved by Microsoft, no action required.