Have a look at
http://www.totalpda.co.uk/forum/showthread.php?t=3330 (TomTom 5 setup problems BT GPS READ THIS)
I have the same PDA and it works fine now
Click on tomtom navigator
Tap on the screen and select Change Preferences (big spanner)
tap the black triangle until it says Preferences 4 of 6
Select Configure
This is the stupid part Select "other cable NMEA GPS" yeah thats right CABLED
GPS Baud Rate 4800 and select DONE
Select the correct bluetooth port (for you COM5), if you cannot see the number tap and hold and then you will see what number.
You will notice a small orange and black circle at the top right this will start to spin if you are connected to the GPS if it does not spin then soft reset the PDA and try again.
Edited due to customer feedback
if it still fails and you are going from 3-5 then try below.
Process:
- uninstall Nav 5
- Reinstall Nav 3
- Install 3.07 patch (if not already installed as above)
- Remove TomTom Navigator ONLY from the remove programs list.
- Reinstall Nav 5
- Run Navigator, go to GPS setup and, for me at least, use tomtom bluetooth selection.