Thanks for the replies guys, will get back to you when I've had time to have a look at the options.
One thing I did do was uninstall my TomTom programme as I plugged my satnav into the computer last week and had a few issues with it as it kept relaunching itself after I quit it so I'm wondering if that's the cause of the snarl up. Should find out whether that's done the trick soon though.