That's strange. I have used a hewlett packard keyboard and dell usb keyboard and usb keyboard case and they all worked. I have also used a usb dell mouse and that also worked.
Logitech Wireless usb mouse didn't work for me though.
Is usb debugging on? I heard that usb debugging has to be on for usb devices to work. It's on for me.
I bought one of the ones from Amazon but it doesn't seem to work. I tried a regular Microsoft usb keyboard and an HP mouse with no luck and a wireless Gear Head keyboard/mouse combo with no luck. I did have usb debugging on. I'm going to try the one that Pandigital suggested in there link. The one I bought from Amazon had HDE in front of it so maybe I got the wrong one, it looks the same as the other one but who knows with Pandigital products. It only cost me $1.30 so I'm going to try another one.