Thanks for the advice, but I\'m still not having any luck.
I upgraded the firmware on my access point as you suggested, and tried various settings (64 bit instead of 128 bit; Open vs. shared key. etc.) and still no luck. I am using a D-Link access point (DWL-2000AP).
The website for the driver says it does not support WEP with the standard Sharp ROM, althoug this could be an old comment. Any other suggestions?