You should not have to uninstall Parallels. Version 5 was meant to resolve the blocking of the network printer. Also, if you still had Parallels 4, the v10.26.2 driver for the MX850 was meant to resolve the issue with the printer not being seen.
So, here is a link to the v10.26.2.0 driver.
http://support-au.canon.com.au/contents/AU/EN/0100105002.html
Note that the printer and scanner are both added via the Default view. If neither of them is appearing in the Default view, then there is a Terminal command that you can run that will stop the Parallels network services. This will save you having to uninstall and will help us identify if Parallels is a cause.
This is the command you can enter into Terminal.
sudo launchctl stop com.parallels.desktop.launchdaemon
you will be prompted for your password. Enter this and then exit Terminal. Now open Print & Fax, click Add and select Default. Does the MX850 appear as a Bonjour Scanner or printer?
Message was edited by: PAHU