I know this is an old thread, but I also know that it discusses a common problem. I run Windows XP on a Sony Vaio. Some time ago, the computer refused to recognize my printer. I tested the USB ports with other devices - which were recognized - and tried another USB cable, which did not solve the problem. I finally decided that the printer was at fault, and attempted to reinstall it with no success. Thinking it was broken, I bought a new one. When I tried to install the new one, although the new program files appeared in the directory, there was no installation of the printer. After Googling the problem for about the fifth time, I tried this : I disconnected every device, I switched off the computer, I unplugged it and left it overnight. And guess what - it worked! Fortunately, the shop refunded me for the new printer, because my old one installed straight away.