Try Reinstalling your Printer's Driver. Close All Applications before starting the Uninstallation/Installation.

Check and tell if its working.

That's what Dell recommended, too. I tried it, but Firefox was open so that I could download the new driver from dell.com. Does that count as an open application? It still had the same problem after reinstalling the driver. I have also reset this printer in Firefox by using the "about:config" command in the address bar and right-clicking "reset" on the printer. Someone suggested changing the version of Firefox back to 5.0.1, but I'm nervous that might cause more problems, like incompatibility with certain plug-ins. Is it worth reinstalling the driver a 3rd time, or is there anything else that I can do?

• Restart your System
• Uninstall your Printer
• Restart your System
• Plug-in your Printer with the Computer
• Install the Printer Driver from the Printer's CD/DVD

Check and tell if its working.

I completely uninstalled the printer and drivers and restarted the computer. I then uninstalled and then reinstalled Firefox 7.0.1, restarted the computer and then reinstalled the printer (from the previously downloaded exe file, because I don't have the CD for the printer). Unfortunately, neither of those things worked, but I did notice that when I uninstalled Firefox, it asked if I wanted to save settings, and I said yes and it seemed to remember the Dell 720 printer in the "about:config" menu. So, maybe uninstalling Firefox without saving settings would make a difference. What do you think? Also, I just noticed in the "Add or Remove Programs" menu in control panel that the icon next to "Dell Photo Printer 720" is a little recycle bin, which seems a bit odd. On the dell.com forum, someone suggested using Firefox 5.0.1, available at a different website. Is this worth a shot or are there other more conservative troubleshooting suggestions to try first?

Create a New Profile as a test to check if your current profile is causing the problems.

-> Basic Troubleshooting - Make a New Profile

IF that New Profile works then you can recover your Bookmarks and Passwords from the Old Profile.

-> Recover important data from an old profile

Check and tell if its working.

I completely removed Firefox 7.0.1 and replaced it with 5.0.1, and now I can open printing preferences. Follow these directions:

Create a system restore point first if you want.

Then, go to start, control panel, programs and features. Uninstall Mozilla Firefox.

Go to...

If 32-bit... C:\Program Files

If 64-bit... C:\Program Files (x86)

And delete the Mozilla Firefox folder.

This should give you a fresh start. Then install the older version. Bookmarks can just be imported from Internet Explorer or saved prior to switching versions