Windows XP, USB2 ports. Likely this is a software problem but not sure where to start. My computer stopped recognizing my digital camera and camera dock that plug into USB. Still recognizes my printer and scanner. Bought a card reader thinking I'd bypass the problem but it wasn't recognized either. Later added a UPS which hooks up to USB so it can be monitored and it wasn't recognized. I get a beep when I disconnect or connect them. It doesn't matter which actual port I use. I can take the printer out and put it back and it sees it every time. Using install new hardware it wants a disk with a driver on it but when I supply that it doesn't find it. Troubleshooting through Microsoft's system doesn't do it. Using device manager to try to find them shows only question marks where the device should be. When I plug my camera into another computer it's never been used on it is identified correctly by model immediately. This did work for years but I've screwed something up, perhaps with some kind of maintenance software but I don't know what to replace. Tech service associated with my computer think I may have to do a factory install which seems like a major headache. Any ideas? Thanks.