Unable to send or receive messages for the Hotmail (...) account.

Server Error: 4402
Server: 'https://mail.services.live.com/DeltaSync_v2.0.0/Sync.aspx'
Windows Live Mail Error ID: 0x8DE00002

I received this message a couple of days ago.  As far as I know I haven't done anything that would have caused this message.  I don't understand the message so I am unable to fix it.  Hope someone can help me.