for what it's worth, I have a wd green 1 TB drive and the antec mx1 setup for my livingroom dvr (hr-2100 i think). It works, but I've had to get into the habit of rebooting my box and external drive once a week. If I don't the drive gets to a point where it freezes, studders, etc. not a big deal, but I've wondered ever since if I should not have gotten the green drive, and instead gotten the whatever is the equivilent non-green drive. I love the extra space, and would not want to give it up, but next time I think I'll try the non-green version, what ever that is. Green drives were meant to spin down as far as I know, and in a dvr, they most likely dont. I'm sure someone will correct me if I'm wrong?
I think you're correct. They don't stop or slow down at all as far as I know. Your problem might be the 100. I haven't seen many posts about those green drives doing what you are describing. I use Seagate drives in my Antecs and have no problems with them. Why don't you see if WD warranties those drives and get a replacement? WD will probably test the drive and send it back to you if it is OK. The Antec enclosures are remarkably stable and I've not seen any posts that I can recall where the Antec caused problems such as yours. If WD sends you the original drive back and says it is OK, I'd consider getting a replacement for that 100. Unfortunately, you'd probably get another 100 to replace it.