Hi Aaron,
If your users will only be using Windows virtual machines, there's a chance you may be able to work around the issue by downgrading to Fusion 5.0.1 until the underlying problem is fixed. Here's the download link. (Please double-check that the selected version is 5.0.1 before downloading!)
A fix for the issue is in the works, but I can't say when it'll be released.
Thanks,
--
Darius