I'm using Ubuntu 10.04 on EEEPC 901 (Ralink rt2860). I had this bug too.
With the new release, I also had the bug #496093
(https://bugs.launchpad.net/ubuntu/+source/linux/+bug/496093) : no connection
to WPA/WPA2 mixed mode wifi.
I followed the instructions in the post #190 of the previous bug, in
Updating drivers ad described in comment #190 works perfectly with eee
901, and it fix also the wifi-n-connectivity bug
(https://bugs.launchpad.net/ubuntu/+source/linux/+bug/442178)
--
[lucid] rt2860 frequently fails to connect to mixed mode WPA/WPA2 secured
wireless networks
https://bugs.launch