When launching bootcamp partition VM, recieve "Cannot open the disk /Users/%user%/Application Support/VMware Fusion/Virtual Machines/Boot Camp/%2Fdev%2Fdisk0/Boot Camp partition.vmwarevm/Boot Camp partition.vmdk' or one of the snapshot disks it depends on." (Where %user% is your MacOSX user shortname.)

The trick is to just delete  BootCamp partition.vmwarevm file. (Technically, a bundle folder.) This forces VMWare to rebuild the settings as if it were launching it for the first time.

Info found at http://lonewolf-links.blogspot.com/2007/09/mbp-w-bootcamp-seamless-hdd-upgrade.html