i installed exchange 2007 update rollup 4 today and after restarting the server, Microsoft Exchange File Distribution and Microsoft Exchange Service Host service is stopped. It is set to Automatic but does not start. I uninstalled the rollup and service got start automatically. then i installed Update rollup 3 and the same problem. it has happened with me on three different servers. 2007 is in the exchange 2003 organization (we are in transition phase). I tested OWA and it was working fine.
I searched on Internet and found http://support.microsoft.com/kb/944752/
artical but it looks very complicated to follow. and could not found the patches mentioned in the artical.