Comment # 87 on bug 920937 from Oliver Neukum

(In reply to Ian Powell from comment #86)

> I've just rebooted system and printer (both powered off) and discovered this
> if i run "/usr/lib/cups/backend/usb" lots of times it always gives back the
> correct information (comment #75) but as soon as i run "lsusb -v -d
> 04e8:329f" once and then run "/usr/lib/cups/backend/usb", it then fails (as
> per comment #79).
> 
> I tested this twice with rebooting because at first i thought it was a
> coincidence.

Probably not. Your device appears to have a buggy firmware, which doesn't allow
certain descriptors to be retrieved twice (Windows doesn't do that. lsusb or
its equivalent do so)