'Printer may not be connected' - but works fine via Virtualbox guests

[BoundaryNoob]

I am running Jaunty (Ubuntu 9.04 Kernel version 2.6.28-15)

I have a Canon Pixma ip4500 printer that appears to accept print jobs but then stops before any mechanical response from the printer. A status message 'Printer may not be connected' appears in the print manager, and Printer state is shown as 'Processing - unable to open device xxx : Permission denied'.

I attach a png showing the messages and can send a (long) output from the Printing Troubleshooter if this would help.

A few observations:
- It used to work fine under Hardy.
- I recently tried Turboprint but had difficulties with it too and uninstalled it. Installing Turboprint may have been the part of the problem and upgrading to Jaunty may have been a factor too.
- I have tried re-installing the Canon drivers downloaded from the manufacturer's website
- I am running Windows XP and Linux Mint guests under Virtualbox, and the printer works fine in both cases (i.e. via the Jaunty host that's got the problem).

Anyone got any ideas?

[BoundaryNoob]

Sorry - I put this on the wrong forum - will switch it to Hardware and Laptops