Not the most recently replied to topic i know, but this happened to my fiancee's wii aswell.
The console itself appeared to be functioning fine, would load games etc and boot to the main menu, resync didn't do a thing, because you basically couldn't. Swapping batteries made no odds, although i knew this wasn't the problem in the first place.
Next step i simply unplugged the power cable from the back of the wii for 5 minutes and plugged it back in, powered on resynced the controllers and its been fine ever since.
I think the console needed a 'reset' obviously it had crashed somehow on the RF side of things, i assume this remains active even when the power is off to receive the power on signal from the wii mote, so i'd guess it had crashed causing these issues.
Might be worth while taking note of if nothing else works
