Print error ONLY printing from Internet

Error Message “There was an error writing to LPT1: for the printer (HP DeskJet 720C Series):
There was a problem printing to the printer due to an unknown system error. Restart Windows, and then try printing again.”

Originally had no problem with same printer and computer. Problem began about 8 months ago. Only new hardware connections: HotSync cradle/charger for Handspring PDA.

System Information:Dell Precision Workstation 220. Pentium-3/728MHz. 512 MB RAM. 20GB HD.

HP DeskJet 722C
Port: LPT1.
Location: Local
Data Type: EMF
Print Processor: WinPrint
Driver Name: HP DeskJet 720C Series v10.3
Status: Normal
Driver Version: 4.0
Technology: Raster printer