Computer Usb devices?

My computer is now very temperamental with usb devices and im wondering if there is any way to fix this. When i try to install a usb device ( my printer/ ipod/ camera) an information box always appears saying they have not ped the LOGO tests. I have used my printer for a good two years, and didn't have this problem before. Also, once i continue to install it it says it cannot find files such as usbscan.sys and various .dll's. I manually locate these files, but the peripherals just dint install. there always seems to be some error. I'm scared i have deleted something and need help. All the files it looks from come from service pack 3, but i don't have any installations disks at home. Thanks