USB devices not seen. Hi. My usb devices are not being seen by my pc, but when I disconnect each

Question

Hi. My usb devices are not being seen by my pc, but when I disconnect each one the pc states "one of your usb devices has malfunctioned." This happens on all of the usb ports. Sometimes I get the device to be seen after about the eighth re-start of the pc. The devices i have used include a Tom tom satnav, a Goodmans camera and a Lexmark 1100 series printer. At present the Lexmark disc is stating "you have not connected the printer." There is a Canon printer connected up too which has never given any problems. I am running windoze xp SP2 with about three registry problem fixer programmes. The problem was no better or worse before the registry programmes were installed. Thanks.