Edit: Just updated RO in steam, still same crash and error when i try to join that server.
Please follow these instructions to verify your RO Game Cache, as that sounds like the problem:
In Steam, in the My Games Tab, right click on the RO launch icon, select properties, select the local files tab, and click Verify integrity of game cache.
When you "Verify the Game cache", Steam will update.
If that does not work try deleting your whole RO system folder.
Verify your RO game cache again.
Hope that fixes it