TomTom One - T-Mobile MDA II data connection

Im having real problems getting my TomTom to remember the mobile phone data connection settings.

Specifically with Traffic Info. I set up my TomTom and phone to use Plus Services. It works fine until TomTom tries to update the ttraffic data at which point I get a red screen saying that the connection cannot be found.

I then go through the whole connection setup process and TomTom works until the next time it tries to update, when the whole error and setup process ocurrs again. Its doing my head in and devaluing the traffic info service.

I have the latest software installed. Has anyone got any ideas? Cheers