I have the same problems: I had a HP desktop with Win 7 Home Ultimate and 3tb of USB attracted and purchased a new HP laptop, same OS.
Set up Homegroup and everything was shared, could read/write. the the HP went belly up so HP gave me a new HP desktop, same OS.
Hooked up the 3 USBs with 3tb to the desktop, and JOINED with the laptop.
Then the problems, suspect it is the CREATOR OWNER Crap cause the data on the USB was created on the old HP, same OS but it seems to know it was different.
What I want to happen is to add yet another PC with more "foreign created" disk but can not if can not get the 2 new HP to share.
I would like to make EVERYTHING to SHARE with EVERYTHING since i am the only user. BUT, Microsoft seems to be bound and determine to NOT us share without ourselves. Don't think there is a way to SHUT down all these crappy permissions. Tired of trying to get something done and getting "ACCESS IS DENIED" or "the FUNNY one "YOU dont have the permissions" as I AM the only one using these PC or access to.
ANYONE found a way around without going back to XP pro which NEVER gave me any problems. The problem then is it violates my warranty with HP.