I've somewhat partially solved the HDD issue. Since the TV only reads FAT / FAT 32, I had my 320gb HDD converted from NTFS to FAT32. And the hard disk is being read now. But, but, FAT32 cannot store individual files larger than 4GB so I only have movies less than 4GB. This is not really an ideal solution but may work in the short term.
I'd like to know if a firmware update helps the TV read NTFS file systems (this is the default for most HDDs).
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One more issue: movies look good, maybe too good that it looks like a TV serial:sad:. I did some Googling and this is a universal problem with many TVs (Soap Opera Effect) where the images look smoothened out and make them look unrealistic. I'm currently checking if there are any settings that could fix this. Article about the 'soap opera effect' - The Soap Opera Effect: When your TV tries to be smarter than you | Common Sense Tech - CNET News
I am bit confused when you say that ST50 reads only FAT file systems. In fact I have created NTFS format on my USB memory stick and played few movies with out any problem. can you please clarify ?