After rollup 2 for OWA on Exchange 2010 SP1 OWA stopped working alltogether. We got the basic client to work(kinda) after setting the default language, right now there are two issues.
1) premium client doesn't work
2) basic client can't open any attachment or follow a URL w/in an email, trying to open an attachment or click on a link within the email pops up another window that displays the current basic client
We have had an incident open with Microsoft for nearly two weeks and no solution.