I was told to come back here and add additional details. As you can see, I couldn't be more thorough in my description of the problem. I can print, but can't scan. Tried the printer on another computer (same drivers) worked fine. Tried other USB ports on first computer, still can't scan. The "copy" function on the printer console will copy, but the "scan" still won't. Everything works as expected on different computer.
XP must be using a built-in driver for printing, but without the install files the scanner is inop.