With most printers the “test page” is generated from the printer’s on-board operating system, not the computer’s software. Perhaps the printer software has become corrupted. Try reinstalling it from a download or the original installation CD.
Yesterday I visited a relative that has a HP printer that didn’t print, even after reloading the updated software from the HP website. (The printer could print it’s own “test page,” but nothing else.)
What did I do? In the Control Panel I deleted the printer. After that Windows XP popped up a “found new hardware” message and then XP went on to install the printer. Then I printed the first page from a randomly selected website. That printed page showed that both ink cartridges are short on ink, but at least the printer is now functional.