xsane can't detect my CanoScan FB330P scanner

[hazel]

I am trying to get a Canon CanoScan FB330P scanner to work with xsane but xsane refuses to detect it. According to the sane documentation, this scanner is well supported by the canon_pp backend when using a parallel interface. I have made the following checks:

1) libsane-cannon_pp.so present in /usr/lib/sane. OK
2) canon_pp listed in /etc/sane.d/dll.conf. OK (it was commented out but I have uncommented it)
3) canon_pp.conf present in /etc/sane.d. OK. The active lines are:
ieee1284 parport
calibrate ~/.sane/canon_pp-calibration-pp0 parport0
init_mode AUTO parport0 (I have also tried with init_mode FB630P with no
better result).
4) /dev/lp0: I have made this world read/writeable.
5) /var/log/messages: no xsane errors as long as the hpiod daemon is running.

Can anyone suggest what I should do next?

[hazel]

Update on this:

The scanner is detected if I invoke xsane as root. I get a severe scolding from the program but at least the user interface comes up. However I still can't scan with it. If I press either the "scan" or the "get preview" button, the scanner goes into action but then the whole program freezes up completely. So now I have two problems! How do I get my scanner recognised when I am not root and what is causing the freeze?