I just installed two ink cartridges in my HP Photosmart 7250 and every time I try to print it says the yellow cartridge is empty and it will only print in black, not color, but when I select black only it prints all the colors fine and the ink levels show they are all O.K. The printer also says if I don't replace the yellow cartridge (which is full) printing will eventually stop. How do I fix this?

I just had the same problem on my printer and found that resetting the printer solved the problem.

1. To reset this printer, make sure the printer is on. Unplug the printer without turning the printer off.
2. Wait 60 seconds.
3. Hold down the # and 6 button while plugging the printer back in. Keep holding the # and 6 down while the printer turns on. After a bit, on mine there was a picture of the power symbol that appeared on the printer display.
4. When the power symbol appears on the printer display, take your fingers off the # and 6 button.
5. Push the power button to turn the printer off. Push the power button again to turn the printer back on. The printer will take some time to go through some preparation. When the preparation is complete, the printer will recognize that the cartridges are full.