In win xp sp3: HP1120C prints test sheet in living color as advertised...but

The printer driver (file) is probably damaged (from frequent use); after your hard disk is stabilized (by running "chkdsk /r /x" from a command line [cmd in Run] and setting it to run on next boot), I suggest downloading the driver from HP Support and reinstalling it; then log off or reboot and select it as default if you want. Logging off, like rebooting, resets all hardware drivers.