Something is seriously screwed up here and I can reproduce the problem.
On most of my ActivePerls Group.pm is in perl/lib/GD, but it's not there in build 1004 (5.10.0). I don't know whether it was *never* there, or whether 'ppm install GD::Simple' removed it.
Which build of ActivePerl do you have ? Simply reinstalling it might fix the problem (but only if GD::Group.pm ships with that distro.) Otherwise, let us know, and we'll devise another way of getting it fixed.