Hey, loving the game so far, however I have had some very peculiar issues when playing with my friend in game. 

1. Completing a floor and experiencing a crash (my end):

- Upon escorting the crystal to the elevator, pressing the "next floor" button freezes my screen

- Frozen screen leads to windows providing a "this program is not responding"

- Friend still progresses to next floor

- I am hosting

2. Completing a floor and not progressing:

- Upon escorting the crystal to the elevator, pressing the "next floor" button

- Friend Progresses yet I am left on a floor with no alien spawns

- Can still move

- Me or a friend is hosting

The screenshots are from where we attempted to work around the issue, by making the game just my instance only (he left the game). After several seconds, the button re-appeared for me and I had control of his character, yet when I press the button, it freezes white and am left on the floor with no alien spawns.

3. Mid Level "Freezing"

- In random timings Wizzerd695 (In screenshots) will freeze for myself and another friend.

- Monsters will also move to other rooms and will sit idle

- I or my other friend will not be able to attack until we open another door, this does not fix the existing monsters/Wizzerd695

- Because he is not in the elevator on either myself or my other friends screen, we can no longer progress due to the button being 2/3, 2/4 or 3/4 (depending on if we have recruited another hero)

- Me or a friend is hosting

System Specs:

Processor: Intel i5-3570 @ 3.40GHz 3.80GHz

RAM: 24GB

System Type : 64-bit, Windows 7

Resolution:1920x1080

My Game Directory/VERSION:

Version: 1.1.5

Dungeon of the Endless.rar

Should probably be noted that I have completed the game with a friend and have had no problem with the mechanics or any bugs, it is only when I play with a specific friend (Wizzerd695) that we encounter issues.
I believe he runs on Windows 10, and I don't know the specs of his system. Could the difference in OS be whats causing the problem?

Thanks for your time and trouble, Narnian.