Disconnects for what period of time?
There are a few people who have had problems w/ macbook air's.
(less often I think w/ macbook pro's)
In general, people seem to think these problems can be resolved w/ enough tweaking to the controller configs, but I haven't figured out what the magic incantation is that makes things work.
I'd open a case w/ Ruckus.
Try to only make one change at a time, and make notes re: what changes caused what improvements.
I had issues w/ macbook air's roaming frequently between APs, and also brief (but sometime frequent) periods of connectivity loss.
Things seem to be better now.