MPT V4.21a problems

I have just installed MPT V4.21a and am having a number of issues. I have a
GSM V3 RAZR and a V551 that I would like to use this software with. The
software is a downloaded upgrade from V4.12 installed from a Motorola OEM
CD. The software came with genuine Motorola USB cables for each phone. I
have tried the software on two different computers with the same results.

When I attempt to use the RAZR, after finally getting the USB driver to load
and the software to connect to the phone, I was able to open the Media
Studio one time and upload/download content to the phone. Since the first
time this worked, now when I open the Media Studio, I loose the connection
to the phone. I can sync my phone contacts, but am unable to use the Media
Studio at all. This happens on both computers I have the software installed
on.

The V551 will not connect to the software at all. The windows driver
installation fails. Windows recognizes that a USB device has been connected,
but cannot recognize it.

I have followed the instructions that came with the software exactly. Both
computers are running XP Pro SP2 and are completely up to date with all
available patches installed.

Sorry for the long post, and thanks for any and all ideas.

KB