Has anyone else had this problem?

I hooked up my SGI-5b box with the T56, adjusted it pretty close, and all was well. Then after a week or two I was driving down the road and for no apparant reason it just died, no more power light or anything. Of course my speedo shut off and set the CEL. So I went to restart the car later and the box was back on. Again as I was driving along, for no apparant reason, it shut off. Hmm I thought, and shut off the car at the light, then restarted it. It came back on and started working like nothing was wrong. This has happened about 7-8 more times, at random without explaination.

I would like to think I have a loose power connection but with the box restarting upon restart of the car, I somehow doubt it, it's more or less a box problem.
I was just wondering if anyone else had this problem and what you did to remedy it. I'm going to e-mail Dakota Digital and ask them if I can get a replacement.