First things first.
You had a power cut that wrecked your hard drive and Windows XP. This doesn't sound right. Power cuts don't usually wreck hardware. A severe power spike, caused perhaps by a lightning strike, could easily have done that however. If this were the case then there is a better than evens chance that other components have been affected.
You say your dvd player was "working fine before". Was this before the power cut/spike? If so then the likelihood is that it too has been damaged. "When I got back home" sounds like you took your base unit to a PC repair shop. Any competent technician given this information would have tested all your components. If this is the case you could call them again and ask them to check it out. If they are not willing to do it for free then you are looking at either testing it yourself or calling it a day and buying a new one. They are not expensive (compared to PC repair shop fees) or difficult to install.
There is also the chance that other components, sound card, video card have been damaged and are causing the problems. Are other sounds, video images playing ok?
It's unlikely that the problems you describe are software related. Why did you download the trial version of powerdvd? What happened to the software you were using before?