The latest version is 1.0.64, which fixed a couple crash problems similar to what you reported (though I don't recall 2 player vs 4 player maps being an issue, just crashes on a specific 4 player map). GOG released this patch a couple weeks ago, and the Larian Vault before that, so you can grab the patch from wherever you bought the game (presumably Gamersgate, etc, have also released the patch).
If you continue to have problems after updating the game, please email supportdc@larian.com, with a description of the problem and the report.zip file generated by the
Dragon Commander support tool.