Hi sb5917
Have you checked that the settings in your VMC lite are not set to 2g only and are dual mode as this will be causing a problem for you.
Other than this the modem shouldn't change the signal that you receive the pro stick will just allow you to connect at a faster speed your signal in your area will have stayed the same as always.
Can you try your USB stick in another computer and also in a different location to check if this still happens? Other than this you can pop into a Vodafone store so they can take a look at the hardware and check it is working correctly
Let us know how you get on.
Thanks
Matthew
eForum Team