We have a repeating problem with a server whereby once or twice a week the IIS web services reports "Service Unavailable" when trying to access RWW or OWA or any site under the default web site. This does not occur at a regular interval or in line with any other event happening on the server (such as backup).
Companyweb and Sharepoint Central Administration sites still work so i know the problem isnt with IIS itself but something to do with the default web site.
At the point it stops working nothing is logged in the logfile.
No errors are logged in Event Viewer under any of the logs.
Stopping and starting the default web site makes it work again.
This is an annoying problem as it causes phone sync to stop working and remote web workplace to stop functioning.