It turns out that the USB cable is to blame. Changing to a better USB cable solved the Scanner I/O Hardware Error problem. Now I do not need to use the USB 1.1 Hub to force the scanner to work in the USB Full Speed mode.
This also solved the CUPS problem when use the Western Digital Mybook World as the printer server. We are using an image from a Chinese website (http://bbs.qzxx.com/thread-294-1-1.html). It has already done a good job and provide a nice web interface for managing the Mybook World. In CUPS, we need to explicitly enable “raw” printing for application/octet-stream. Please refer to the following two URLs for more information.
Basically what we need to do is to edit /etc/cups/mime.convs and put in this line:
application/octet-stream application/vnd.cups-raw 0 -
Then we also need to install Samsung driver for the Windows Vista, XP and Linux client.