Canon S900 - Manual (Page 161)

Problems Unique to the Macintosh 161
Troubleshooting
Cannot Print in Background
■ Ensure that background printing is enabled.
1
In the Apple menu, select Chooser.
2
Set Backgrounding to On.
■ Check the amount of free space on the hard disk.
Background printing requires a certain amount of disk space.
You may need to remove unnecessary files, or disable background printing.