OK, no one came up with anything at all helpful on this or the other 2 forums, and I did a bunch more testing and diagnosing using a bunch of different MS utilities that other places mentioned, none of which really matters, because they all seemed to tell me the same thing: RPC wasn't working. Not Exchange, not the certificate, not IIS, just RPC wasn't working. So, what I ended up doing was creating a temporary server with Windows 2003 64 bit, installing Exchange 2007 to it, making it a DC (since my other Exch server was the DC, GC and DNS for the domain) I used the migration utility to move the mailboxes from one server to the other. Then I moved the public folder replicas, deleted the Public folder database on the "bad" server, uninstalled Exch. 2007, dcpromo'd it to remove AD, then removed the server from the Domain. (I also moved all the user directories and files and recreated their shares on the temp server edited the login script, Oh and I made the temp server the operations master for all of the Domain/AD roles as well as a GC.) With the "bad" server out of the domain and everything functioning just fine on the temp server, I just wiped it clean and reinstalled from scratch. I installed Windows server 2003 x64, then service packed it, joined the Domain, made it a Domain controller, DCpromo'd it back to a being a DC, moved the DC/AD roles all back to it, made it a GC server, installed DNS and made sure everything synchronized just fine. Then I reinstalled Exchange 2007 and RPC over HTTP Proxy, created a test account on the newly reinstalled server and voila! RPC over HTTP/S worked perfectly right out of the box as it is supposed to. I moved the mailboxes back, did everything neccessary to make Exhcnage 2007 be the way it should be and I was done. What a hassle. But maybe this will encourage someone else to just start over instead of beating their head against a wall, and if it makes it easire for someone else then, this forum will have done its job. By the way in response to the post saying that MS requires a "valid exteranl cert": If you mean a certificate from a "real" CA, this just isn't true. I created a self signed certificate from my server that has Certificate Services on it and it works just fine for RPC and everything else. Just remember to go to https://yourownserver.com/Certsrv and click on download the certificate chain, then install the certificate chain and you'll be fine for RPC over HTTP with Outlook 2003 & 2007. Don't just do the https: to your server and try to click on "install certificate" you need to actually get your self CA into the trusted roots, not just the certificate. The only thing that paying for a "real" certificate from a CA like Verisign or Thawte gets you is that they are in the trusted roots by default and you don't have to add them. If you meant that you have to run the enable-ExchangeCertificate for the imported certificate and specify the services (SMTP, IMAP, POP, Unified Messaging, IIS) that the cert is for, then that was already the case. OK one caveat here, for "locked" mobile devices (the Samsung Blackjack for instance), where they only allow you to install approved apps from the wireless provider, you won't be able to download and install the chain, so for those and (as far as I know) only those locked devices you would need a "real" certificate from a "real" CA that you pay money for. Most other MS active sync or Windows Mobile devices play fair and let you install certificate chains.
Good luck if you are reading this because you have this problem, I can sympathize. -Steve