Preamble: Please acknowledge that I am an experienced admin myself - the cause of this problem is no misconfiguration.
We run an exchange 2007 SP3 (with current roll-up) on server 2008 SP2. From time to time without changing anything, the server runs into the following problem: free/busy info cannot be retrieved and at the same time, the out-of-office assistant stops working on any machine domain wide and says "the server is currently unavailable", please see the attached two screenshots.
Please note: mails are still being received, everything else works.
I have no idea why this happens since
-no reboot took place
-no updates were installed
-no services crash (also a reboot does not help)
-no software was installed, nor did reconfigurations take place
-no related eventlog entries are being produced during that time window
->not at the DCs, nor at the exchange server :(
I only know how I can solve it: simply uninstall and re-install the client access role at the exchange server. Afterwards, it runs for some time (sometimes half a year, sometimes only one week), until it happens again.
Does anybody have a clue about what might cause this?