I have experienced this issue far too often; twice in the past two days and many more times prior to that.
This is absolutely game-breaking, and needs resolution soon.

I have attempted to keep myself on 'whitelisted' servers (though without the ability to filter servers I am not always certain), I have done my best to not switch servers too often. It happens regardless.

I would say that in my 144 hours logged, 90% of my character losses have been caused by this issue.

I understand this is an alpha, and bugs are expected. I knew that when purchasing. However, this issue needs more than just 'acknowledgment' - this is the most severe issue I have experienced (and experienced multiple times) and would like some sort of official response from moderators/developers.

When can we expect a fix? Is this being worked on? Why is this happening? What can be done to avoid the issue?

I have dissuaded friends from purchasing the game by just telling them about this glitch - they are sold on the whole concept of the game, but not the instability. This is the only issue keeping them from buying.

EDIT: Occurred again - 3/18/14; reason unknown.