New drives keep getting marked as bad!

I have now gone through 4 hard drives. Everything was working great for the last while and I heard a drive dying in slot 1. Sure enough, Drobo flagged it and I quickly got it replaced. The data protection went into action balancing out the data and as soon as it finished, it flagged another drive (in slot 2) as dead. Again, I replaced it, and again like the previous time, as soon as the data protection finished and all lights were green it then flagged a 3rd drive (in slot 1) as dead – this is a drive I just replaced. So, again, a new drive and AGAIN as soon as it finished, slot 2 is flagged as dead with a blinking red light! I can’t keep feeding this thing drives. I already feel like it’s not the drives, but now must wait on support (if they will even help me with my out of warranty product).

Anyone else have this happen? I know once a drive is flagged as bad it will never accept it again, so this is getting very expensive and really killing my trust of the product. What can I do?