Each time I finish a dungeon either with a group or solo.... beat the boss it tallys up my exp and gold says if I lvled and passes out loot.
Then the game just closes even though my connection is fine, there is no pop-up about the crash or anything it just all disappears and when I log back on my exp I got is gone and so if my lvl and loot... -.-
That tends to happen to me sometimes if I'm running windowed mode and tab out during the tally. That might be your problem.
Mines closes everytime i switch over to a different tab in windowed mode but sometimes it just does it to piss me off in play of dungeon or pvp. shiits ticking me off