Question about Outlook Express

Two machines, one domain account:

1)  Windows 7 x64 SP1 PC , Outlook 2010 (14.0.6112.5000)  64-bit,

2)  Mac OSX Lion 10.7.4,  Outlook 2011 (14.2.2 - 120421)

On the O2010 machine, I can browse as many public folders as my account has permissions to. 

    Example:   All Public Folders -> Department A3 -> Facilities -> Calendars -> Test calendar

On the O2011 machine I can browse one or two levels from the root, but not to the full depth.

    Example:   All Public Folders -> Department A3

The folders do not appear to "fill in" over time (at least, not overnight). 

The PC is domain joined.  The Mac is not. 

The Exchange environment is a mix of E2003, E2007, and E2010.  All of the Public Folders have at least one E2010 replica.  Access is consistent on both machines.  (i.e. I get stuck in the same place every time on the Mac)

Other EWS clients (e.g. Thunderbird 13.0.1 on both Mac and PC) have the same issue and get stuck at the same places in the PF tree.

Any idea where to look?

Thanks,

Red