It appears to be a common problem click here. If you scroll down you will find a free solution posted on 29 Jan 2008 as follows
"So to do this all you need is Hiren's Boot CD and its containing tool Super Fdisk 1.0. When you enter to it, automatically finds the problem, select yes and it solves it. After you reboot and enter Vista, your disk is back with all your data. No convertion, no need for data recovery just with this FREE super tool."
Haven't tried it myself of course. Googling Dynamic invalid disks will throw up quite a few solutions.