Problem: Exchange 2003 Server will periodically go offline.  OWA will not work and cannot access via Outlook as well. In the past, a reboot or restarting the Exchange services would fix the issue but this problem was different than the past.
 Solution: Realized that the hard drive was running low on space.  Freed up some hard drive space by deleting temp files and old log files. Just like in a previous post, I needed to go back to the basics and check the hard drive space.