I upgraded my older MacBook to Snow Leopard by CD, then clicked to accept the update, which was for 10.6.7. Now I can't print to my Canon multifunction laserjet MF4150. It seems I'm not alone. But now my daughter's MBPro which still uses 10.6.3 (see below) also can't print! First several times I tried to print to my MB, the print monitor showed an "Error" without saying what the error was. I downloaded the latest driver (UFRII_V224_MacOSX_us_EN.dmg). Restarted a couple of times. Now the Print Monitor apears to show the job going successfully to the printer but nothing happens. It happens no matter which application I print from. Checking the printer info settings, the General tab says I have "Driver Version: 2.0". Shouldn't it say 2.24 if that is the installed driver? Even worse -- I decided to check whether my daughter's MB Pro (2010) was still able to print to the MF4150 (worked fine the last time she printed). Printing from a Word document, I noticed that the printer that I could select now said "Canon MF 4100 Series @ Steve's Computer". Sure enough, after the upgrade/update, my computer now had a check in a box for "Share this printer...". I've never used that and don't want that. Unclicking sharing on my MB did not help, as her print setup still identified it as a shared printer. I tried to add the printer to her MBP as a new one. But there is no corresponding driver to select. So I then downloaded the latest driver from Canon.