Broken record incoming.
Don't install ML (or any beta OS) as your primary OS. Ever. If you're needing this Mac to log into remote meetings than clearly it should never have been "upgraded" to ML beta.
Get your machine back down to Lion and you'll be able to access your Web EX meetings no problem. Put ML on a bootable external drive or a test machine if you need to stress test it. I'm sure Cisco will have their app ML ready when it makes its official release.