You have taken the disc out haven't you?
Try forcing a reboot by pressing <,>, & I (or whatever your button is next to eject) for about 10 secs until the unit reboots.
If that doesn't work then press Setup, Eject & I (Or whatever the button next to it is) The unit will go through a power cycle and will initially ask for a SWL CD on a bar at the top/bottom of the screen but then it should sort itself out after a couple of mins and may require you to turn it off and back on again.