If my previous answer is wrong, you might also want to check and see how many printers appear to be installed on your PC.
In the past I have had a problem where a copy of the printer appeared as an installed device, with the copy being the default printer, even though it did not physically exist. I never did find out why it happened, but I suspect it was one of my children unplugging the printer at the PC end, printing from a laptop and then reconnecting the printer to the PC in a different USB port.
If that is the case, make the original printer your default printer and then delete the copy. In Win7 from the start menu, click on Control Panel, then on Hardware and Sound, and then on Devices and Printers. That will show the devices and printers your PC knows about, and if there are two identical printers (one might have a name that includes 'copy'), right click on thre one with a tick (indicates the default printer) and select Remove device from the pop-up menu, then right click on the remaining one and click on Set as default from the pop-up menu.