I'm just curious to see how widespread this issue is. My log has quite a few of these messages, and the constant connection drops are getting annoying. Firmware version doesn't matter, and I exchanged the router (going from HW A2 to HW A4 in the process) with no improvement. No 2.4 GHz phones, either, or any other sources of 2.4 GHz interference that I am aware of or have control over.
So, log in to your DIR-655, click logs, hit control-F, and type "wireless restart." Do you have any that weren't preceded by configuration changes (that should, presumably, restart the wireless)? I am wondering if this isn't happening to more people than are aware of it because they haven't looked at the logs.