This is what you have to do:
- First be sure the printer is NOT connected to the computer.
- Go here on HP's support site and download the driver "Version 2.0" updated 9 Nov 2010: HP LaserJet Hostbased Plug and Play Basic Driver. (7/12/2015: HP keeps moving the driver. Here it is today: http://support.hp.com/us-en/drivers/selfservice/HP-LaserJet-P1100-Printer-series/4110394/model/4110306#Z7_3054ICK0KGTE30AQO5O3KA30R1)
- Once downloaded, find the driver (it will look like this: LJP1100_P1560_P1600-HB-win64-en), right click and choose "Run as Administrator".
- Plug the printer into the computer when the install process asks you to do so.
- Finally! (You may need to shut down and restart your computer.)
It is possible you need to do one more step:
Go to Control Panel \Hardware and Sound \Devices and Printers and find the printer. Although you likely tried this before, right click on the printer and select troubleshoot. It likely didn't work before because the driver may have been corrupted. So try again after completing steps 1-6 above.