Canon printer will not scan with OS X 10.8

I have a Canon MX870 printer. When I upgraded to OS X ver 10.8, my scanner wouldn't work. When I opened Canon's MP Navigator 2.2, a window opens & says "MP Navigator EX quit unexpectedly". I downloaded the driver for 10.8 from Canon. So I now have MP Navigator EX 3.1 instead of 2.2. When I open MP Navigator EX 3.1, a window opens & says "MP Navigator EX quit unexpectedly". Please help!