We use a PR4100 (firmware 2.30.1830) hooked up an AirPort Extreme to run a small business network. About a month, the NAS began to disconnect from everyone every 15 minutes or so after a reboot or a restart. I hardwired it to my Mac powerbook, and it did the same there. WD sent a replacement, and lo-and-behold, the exact symptoms prevail. New box, still kicks everyone off after about 15 minutes.
Whoever cans love this for me, will get a case of beer shipped to them!!!