I've just installed 12.04 on my home desktop. Because of where it's located, in order not to have my children tripping over cat5 cable, I've got a cheap 802.11n USB device plugged in, which uses a Realtek 8192CU chip. The house wifi is protected with WPA2.

Ubuntu's Network Manager detects the network, but connecting to it just times out and asks for the password again. I'm sure I'm using the correct password. No other computers on the house network are having any difficulty. This device previously worked correctly with both Windows 7 and OpenBSD in the same machine.

The linux-firmware package is installed (from the disc) at version 1.79, and /lib/firmware/rtlwifi/rtl8192cufw.bin is present. dmesg|grep rtl only shows the "loading firmware" message.

I've tried Google, but I apparently can't find the right set of words to plug in, because I haven't found anything related (lots of "doesn't work at all," but nothing matching my circumstances). Any help would be greatly appreciated.