this is the 2nd half of #741728-9: Compatibility with CCK3.x multigroup

multigroup is expected to act as a whole field,
therefore enabling part of its contained fields is NOT reasonable and shouldn't be allowed
bug admin UI doesn't constraints this yet

until now, when enabling fields within a multigroup you have to manually enable them all or none

pending: admin UI constraints for the above,
and having unified settings for the whole set of fields within a multigroup
instead of each field having its own

this is postponed until an official release of multigroup exists (either D6 or D7)
#695636-8: Figure out whether Fields API and Multigroup module can coexist
#494100-58: State of the multigroup module

in the meantime, manually ensure you enable/disable all the properties within a multigroup AND assign to them the same policies (e.g. NEP)
temporary ACP & PCP are disabled for multigroup