My PC (OS: XP Pro) has suddenly stopped being able to 'use' any of the attached devices. At first, only the two internal CD Rom drives and an external DVD (via USB) were not recognised. Now, it does not recognise these or anything plugged into any of the USB ports or even the printer. When I go into Device Manager it lists the devices ("Philips", "Optorite" or whatever) but it has a small yellow circle with an explanation mark in it next to the name. Luckily, the monitor and ethernet connections work (at the moment!). It's a bit of a worry because I can't back-up files. Any ideas anybody? A colleague has suggested problems with the motherboard.