a little confused here,
do you make a partition and format the drive,
that you want to build in the playonHD on a wndows 7 machine?
if so ? Don`t.
just remove all partitions on the drive with windows again,
then build the drive in the PlayonHD,
connect the playonhd to your television,
and switch on the player( don`t attach the player to the PC now)
during start up there will be a message that the drive needs to be formated.
allow this and let the playonHD format the drive itself.
if for some reason the Playonhd does not come with this message,
then after the player is started go to ,
and perform the drive format through the setup menu.
and please do let us know which player exactly it is that you have,
best would be it`s PV number like PV73100 or PV73700 or PV76120?
and which firmware? look for that here setup>>misc>>version (out of my head this one,
but it is something like system version or so