Wireless problem with ATH9k and 5008 Atheros pci card

I have just installed openSUSE 11.1 with ATH9k support in the Kernel.The wireless card will associate to the ap but after approx 10 minutes seems to not work ( ie the rate shows as 1 Mb)and does not come back!
I was using Suse 11.0 with Madwifi which worked well but I want to use the 802.11 n protocol that the card is capable of.
Can anyone please help?