"Signing in to .NET Messenger Service failed because the service is temporarily unavailable. Please try again later 0x80004005"
To fix the issue you have to request that your email address be unblocked from MSN Messenger. This is a one time deal and you can only be un-blocked from the messenger service once so make sure that you have removed any offending software add-on's before asking
You can either contact msn if you have a paying msn account 1-800-635-7019 or go to http://messenger.msn.com/Help/ContactUs.aspx for non paying customers and request that the account be unblocked.
If you are encountering this error when signing in, please install the latest version of Windows Live Messenger from http://get.live.com/messenger/overview
After installation, verify that you have the version 8.0.0812. If you are still experiencing the issue, pelase contact Messenger Support at http://support.live.com and choose Windows Live Messenger