Hello,
Please send me your log files from the Xsyon/Log directory (to bugs@notorious-games.com) for when you all crashed at the same time.
Regarding seeing another players account, we need to figure this out right now. It's the first time we're heard of this happening.
When you saw another player's characters, was there one character, or several?
Did you have one character or several in your account? Have you deleted characters?