Unable to get Mt. Lion Calendar to sync with Exchange

The Calendar application in Mountain Lion will not sync with my company's Exchange server. We're using the current build of Exchange, through Intermedia. And I have the latest build of Mountain Lion on my MBP.

I've tried everything short of wiping the hard drive and reinstalling from scratch. I've tried deleting preferences and cache files. I've tried countlessly deleting the account from preferences and trying to resync. I've even tried all of the guidelines here:

http://support.apple.com/kb/TS2481?viewlocale=en_US&locale=en_US

Nothing works.

There is no error message. No dialog prompting me. I get only an exclamation point inside a circle next to the name of the account in the calendars panel on the left. If I click on the circle/!, nothing happens. It used to sync ok, but for a few events it would choke on. And clicking that circle/! would prompt me to retry or ignore those events. To try and correct the problem, I deleted the account from settings and tried all over again. Then, it wouldn't sync anything at all. And that's where I am now.

(And yes, I've tried deleting those events it originally choked on from the Exchange server, but the problem persists.)

I'm desparate. I'm hating Outlook:Mac more and more but this is the only alternative.

Any suggestions?

dt