It shouldn't be strictly necessary to add more voodoo after updating to 9.7 or newer, which it looks like Brian did. I've heard that disabling directed-multicast might help in some circumstances, but IMO Brian should see if the update alone has resolved the issue.
(Oh yeah, be careful about enabling the extra sets of channels in ZD if you have a lot of BYOD devices. While all the Apple devices seem to support all the DFS channels, I've been shocked at how many consumer electronics devices don't have good DFS support)