ok, I figured this out but wanted to post it here so it doesn't get lost. I ran into this issue and fixed it like 6 months ago, then it happened again and I had to figure out how to fix it all over again.

Anyway, basically it's a registry issue. Go into the registry and do a search for the associated SSID. In the same key should be a dword or something for the transRate. It'll be set to 1. Just set it to 54. Repeat the search and replace any more occurrences (I think there were 2 total). Ignore any hits that don't have a transRate dword.

That fixed it for me. Stupid freakin' bug, but whatever.