Hmm..., works for me (except for internal FM content, which always is in MIF format on FM's own internal clipboard). I can copy and paste from Word and all formatting is stripped when pasting using ctrl+v.
Check the user-specific maker.ini in the C:\Users\<login name>\AppData\Roaming\Adobe\FrameMaker\12 folder to see if there is a different specification there (as this maker.ini is read last and overrides the master one in the FM install location).