There has not been another game update.
When this happens, have the host check if any characters are encumbered. There is a known issue that can cause the client to crash in multiplayer when loading or joining if a character is encumbered (the main cause of that was fixed in one of the last updates, but a few people have still run into this). In that case, dropping or redistributing the excess weight, and saving should fix the problem joining.
The symptoms are a little different in your case (system dlls as faulting modules sometimes, for example), but that may be due to the 4 player mod.
