Hi Ashok,
Nope, it is definitely the A+.
You are right, the partition size does not matter. If I plug the hard-drive in the A+ and play a movie, it works. If the hard drive goes to sleep and I try it a while later, the movie (any movie) does not load anymore.
I have multiple DLNA clients (Mybook lives etc) at home and can guarantee you it is the A+ that has an issue here.
Thanks,
Flo