So the silver lining is still that they came through and restored the data, aside from the fact that the old and presumably really old Dropbox client on it went haywire. Yes, Dropbox is free and no I don't expect them to have a file retention guarantee that safeguards my stuff against nuclear holocaust, but I feel for you friend. In this case, storing files is all that Dropbox does. If my harddrive decided to do that intermittently, I'd purchase a new drive and probably mirrored them.

Why not come up with some sort of open-sync protocol where you could have your data mirrored by many Dropbox like services at once