user cannot access usb interface 0

[Richard Kimber <rkimber@ntlworld.com>]

I have a Canon S45 which I have been using with gtkam.  If I run it as
root I have no problem, but when running as user, I get:

An error occurred in the io-library ('Could not claim the USB device'):
Could not claim interface 0 (Operation not permitted). Make sure no other
program or kernel module (e.g. dc2xx or stv680) is using the device and
you have read/write access to the device.
*** Error (-53: 'Could not claim the USB device') ***   

What do I have to tweak to get it running as user?

Thanks,
- Richard.
-- 
Richard Kimber
http://www.psr.keele.ac.uk/