My friend, I am sorry to say, you're probably screwed, just like me. I bought a F55-Q504 and the GPS doesn't work. The computer recognizes the chip, but the software won't talk to it. I can hook up an external just fine and it works with the Garmin Mobile PC software that came with it, and also works with Streets and Trips. I have had the computer into the local and regional depots, and they haven't been able to fix it, though they were able to screw up my FM radio so it has an echo in it now.
I'll never buy Toshiba again, if for no other reason than their customer service is non-existent.