Win XP image 'forgets' video resolution

I am probably doing something wrong but I don't know what it is . . .

When using XP Pro, I set the screen resolution to suit myself and my MBP is happy with it. Often, but not always, when I restart the image, I have to again set the resolution to what it was upon shut down.

Does anyone know what is happening? Is there something I can do to prevent it?

It's not anything more than an inconvenience, BUT if it is curable, I would like to do it.

Thanks