My opinion is still that you have a hardware problem, but where if not the usb port???
Except that it works using Knoppix live CD, suggesting it's a software problem. Also, the same problem occurs on two computers (Latitude and Inspirion).
Thanks for your help and ideas. Regarding not being able to print apps, I just checked out the cups manual noting that you print from the command line and not from inside the app.
original here.