Perhaps a region error? You could try this.
Tony commented this on the videohelp website:
Had this unit for over a year now.. it started playing up , when just out of warranty.
As previous poster I have disabled the awful blue LED's, the fault is that it struggles to finalize dvd's, and is very jittery at playback. I have replaced the whole DVD mechanism for a Sony IDE drive, slotted in perfect and now working like a new unit again.
So, perhaps you can fit in a new ide drive yourself?