Click Start and Printers (or go to the control panel and choose Printers)
Right click the HP 4100 and choose Set as Default.
You should see a small circle with a check mark in it next to the icon for the HP printer.
The HP 4100 was already selected as the default (and only) printer for that computer. The black circle with the checkmark appears alongside the printer icon in the printer list. All other applications are printing correctly to this printer. The only problem that I'm having is printing the PDF files.
In the print dialog of Adobe Reader disable the entry 'Print to file'.
That solved the problem. Thank you so much.