Wireless in FreeBSD 6.2 seems to have some issues that cause the interface to drop. No known solution at this time. Do you see anything in the logs at the time of failure?
I was able to check out the logs tonight right after the wireless took it's dump. Here is what I saw:
Jun 30 20:28:41 last message repeated 3 times
Jun 30 20:36:11 kernel: sis0: discard frame w/o packet header
Jun 30 20:36:47 last message repeated 4 times
Jun 30 20:36:54 kernel: sis0: discard frame w/o packet header
Jun 30 20:36:56 kernel: ath0: stuck beacon; resetting (bmiss count 4)
Jun 30 20:36:56 kernel: ath0: ath_reset: unable to reset hardware; hal status 3
Jun 30 20:37:19 kernel: ath0: device timeout
Jun 30 20:37:20 kernel: ath0: stuck beacon; resetting (bmiss count 4)
Jun 30 20:37:20 kernel: ath0: ath_reset: unable to reset hardware; hal status 3
Jun 30 20:37:37 kernel: ath0: device timeout
I am having to reboot the WRAP box about twice a day because the wireless problem...