I can't print to HP officejet 4255 all-in-one using Mac OS X 10.6.8

is this printer connected via usb to your computer? via network? working before?

try deleting the other printers in the print window, system preferences, print fax, you say you have downloaded the latest drivers, push the add button, type in the hp model #. Make certain the print que has been emptied. reboot if and try again.

You can always add back the other printers, but isolate this one first, as it is the one you are working on, remember making sure the print que is EMPTY. Make sure your network connections are set for this, or click assisist me.

And no one here has mentioned yet to RESET through System Pref....