Teac dvd recorder

In the control panel, go into "power options", there make sure the settings make sense(that there's no setting that shuts off the hard drive or hybernates the PC after a while its apparently not used).

Failing electrolytic capacitors on the motherboard or a failing power supply sound like a potential avenue of investigation to me. You may be able to detect bad caps with no more than a visual inspection for bulges and/or leaking electrolyte.
Try borrowing a power supply and see if it solves it.

Does this happen with more then one DVD playing software?

Hope you sort it out