Hello,
I'm thinking that your DVR may be overheating, which may cause your motherboard to shut your PC down. Take a look at the rear of the DVR... specifically, the case fan... do you see lots of dust or is it clean? What about the vent holes... clean or full of dust? Considering the nature of your problem, I suspect you will see dust.
If dust is what you see, then a can of compressed air is what you will need. To fix the problem (for now), have the inside of your PC cleaned with compressed air. Also... chances are that your DVR was not built with adequate cooling. You may want to consider getting additional case fans to help keep the temp. down.
Other suggestions would be to keep your DVR off the ground (where it is dusty), off of carpet, and out of confined spaces where it may not vent properly.
Lastly, you may be able to learn the manufacturer of the multi-capture PCI card. Have the card checked, and see if their are any identifying markings. If so, then go to
www.asiansources.com and try locating the manufacturer. If found, and email to them would not hurt... however... given the language barrier, don't be surprised if you don't get much help.
If this does not do the trick, check back with us and we will see what else we can do to help.