i was able to troubleshoot my wii issue tonight and it seems to be fixed...wii has been connected continuously for over 30 minutes now

i have DIR-655 A3 firmware 1.10 with charter cable modem on dell dimension 4600 with windows xp home. i had it set with WPA/WPA2 security settings, but on wii tech support site, under instructions for manual online setup, they list that wii only supports WEP, WPA, or WPA2, no combo of WPA/WPA2, so i changed it to WPA2 only, and that seemed to fix it.
i do have the WISH feature enabled, and MAC filtering, but i don't think either have anything to do with it, as it was happening before and after they were enabled.
if you are still having trouble, try changing your key, and reconfiguring your wii. maybe that will help. if you are more technologically savvy than me (as most people are), maybe you can do the manual configuration on the wii and figure it out that way.