Likewise, when trying to select the print quality, only 'Standard' and 'Custom' are selectable both 'High' and 'Fast' are grayed out.

I am able to check the 'Duplex Printing' box, but the 'Print Area' subsection below is completely grayed out, and since it defaults to 'Use reduced printing' instead of 'Use normal-size printing,' printing double-sided is impossible, unless for some reason I want everything to print extremely tiny (why IS 'Use reduced printing' the default duplex setting, anyway? Even when nothing is grayed out, I have to manually tell it NOT to print everything super tiny every damn time I need to print double-sided, which is pretty much every time I print!). My problem is that sometimes when trying to print PDFs (in both Preview and Adobe Reader), certain options in the print dialog are grayed out and therefore not selectable.

I'm running Mac OS X 10.7.2 with a Canon PIXMA MX870 (driver version 10.51.2.0). I know this is an old thread, but I thought I'd mention that this solved the issue for me.

How to print two sided on mac