Try going into the console screen, enter the Extended tools menu: ctrl. + alt. + x
Then select Delete contents of units. This will reboot the system, then see if you are able apply the VG0. Also could you provide a better description as to the type of system components i.e. CPU, RAID controller, IDE, SATA, SCSI or FC..... and so forth. This helps us tremendously as it is so difficult to understand without knowing what components are in use.

Thank you,

To-M