Why would a printer print out code just by turning the printer on? -

My friend has a Dell desktop computer with Windows XP, a couple of years old, and he was able to print just fine for awhile. Now, every time he turns his printer on, it starts printing 21 pages of small code. If he shuts it off and then turns it back on, it starts over. He switched printers and it still did that. He has uninstalled and then installed the printers each time. He has also checked to see if there are jobs waiting to be printed and nothing shows up. Any ideas?

Could be a virus, perhaps try reinstalling Windows XP?

than dont turn it off?? just leave it on for 24/7/365