Which disk mode do you have configured for these VMs and if they were migrated from an earlier version of ESX did you upgrade the virtual hardware at some point?
I'll have to check the disk mode tomorrow (Home now) but yes I did upgrade the hardware when I upgraded.
Disk are in Persistent mode - and grayed out so I can't change them.
Problem Solved - it seems that W2K vm do not automatically upgrade their virtual hardware when upgrading from SC2.02 to 2.5 or ESX3.02 to 3.5 - so to solve this problem right click on the vm and manually upgrade the virtual hardware - you'll get a warning saying it will no longer work on older versions of ESX - say yes and you're good to go!
Thanks for reading