Your problem may be due to unsupported media - such as using Dual Layer disks, or a data type that is not recognized - such as Divx.
Videohelp.com maintains a database of DVD players and their limitations. Limitations are in the form of acceptable media, data format saved to the media, etc. Additionally, there are some 40 individual comments on this player, too. There's far too much info to paraphrase here, so I'll direct you to your player via this
link.
I think that once you know what types of media and format of the data your player can read, you'll be in good shape. Please rate my reply - thanks!