I, likewise, am having a similar problem.
I have a Mita Photocopier with printer module (22ppm laser!) that works fine (except for watermarks, which don't get through for some reason), as well as a Canon BJC-3000 inkjet.
Now, I used to have the Canon working, but due to problems, I had to re-install.
Since I have re-installed, the Canon refuses to print. The spool goes through fine, but the printer does not fire into action.
I know that the hardware is fine, as I tried the copier on the same port (lp1). I have also tried swapping ports, to no avail. The Mita/Laser will work, the Canon chucks a wobbly.
Yes, I have tried a new printer cable. No success.
I have also tried using lpr from the local console to dump a text file to the ports - again, the mita works, the canon does not. Since it doesn't work locally, I think it's possible to rule out Samba as the problem (but I will disable it and test, just to make sure.)
I re-installed a second time, reverting to an old E-Smith 4.0.1 CD - vanilla installation, same as usual. No go.

Please let me know if you work it out.
Cheers,
Antarius