There is a bug in Windows Server 2008 when you are using Exchange 2007 Outlook Anywhere (or trying to use). The server is not listening port 6004 over IPv6 loopback and the current suggestion (by community, not official) to fix this is to disable IPv6 all together. I’ve found a pretty good post that describes how to disable IPv6 and install RPC over HTTP, here’s the link.
PS! This should be fixed in Exchange Server 2007 Update Rollup 5