samba - Jun 2010 - Folders Not Displayed Correctly on XP Clients

When browsing through our samba shares, some of the folders within the
shares will show up as unassociated files in Windows Explorer. This
prevents the folders from being opened. A way to fix this has been to
click on 'Refresh' in the Windows Explorer context menu when
right-clicking on a white space. Then the folders will show up
correctly and can be opened. I've recently upgraded samba to version
3.4.7 on Ubuntu 10.04 and it was after this upgrade that this problem
began to surface.

Does anyone know what is the cause of this or the best way to diagnose
this problem?