wireless card misbehaving! sensitivity screwed?

[ben]

Hi all!
for some reason my wireless network card has fallen over under linux. I 
am running debian kernel bf24
the sensitivity in iwconfig has changed from 1/3 to 1/27240000 (or 
something similar) and the cell readout is constantly changing.
dmesg returns that i am using orinoco.cs 0.9b
the card works fine under windows xp.
I have tried other cards with the same result.
any thoughts?