Crashing in Co-op

Playing with a friend of mine, both druids except he's using the bear and I'm using the wolf. If he's mapping by himself he won't crash but when we play together he'll crash pretty consistently, I myself will not crash at all. at least once a map and sometimes he'll crash back to back 5 times in a row. Really not sure what exactly is causing it as he'll crash regardless of what he's doing.

I am also having constant game crashes when playing in Co-op as Druid. It crashes randomly every 5-10 mins.