Unable to play files on Samsung TV with Amahi DLNA

[pmip]

Hello,

I have set up an Amahi DLNA server and would like to use it with my Samsung 40UE6000 tv. Currently, I can see the server but most of the files get me "Not supported file format" while those that actually play do so with extremely bad quality. I get more or less the same results with Windows Media Player (on Win 7). The weird thing is that the same files read from another source (for instance, a pen drive) are read perfectly by the tv.
Any way out of this?

Thanks,
Patrick