Finally got this game to stop crashing on start up thanks to: TrialMacameau

1: Open Control Panel.
2: Go To Firewall Settings.
3: Click on "Advanced Settings".
4: Click on "Inbound Rules" on the left hand side.
5: Delete Existing Nexuiz Rules from the middle section.
6: Then on the right hand side click on "New Rule..."
7: Go through the Wizard:
A: Program
B: This Program Path (C:\Program Files (x86)\Steam\steamapps\common\Nexuiz\Bin32)
C: Select "Nexuiz.exe"
D: Block The Connection
E: Make sure ALL 3 are selected
F: Name it "Nexuiz Fix"
8: Now go to the "Outbound Rules" on the left hand side.
9: Click on "New Rule..." once you are in the Outbound Rule Section.
10: Again go through the Wizard exactly like you did before:
A: Program
B: This Program Path (C:\Program Files (x86)\Steam\steamapps\common\Nexuiz\Bin32)
C: Select "Nexuiz.exe"
D: Block The Connection
E: Make sure ALL 3 are selected
F: Name it "Nexuiz Fix"

Created as a guide to ensure the fix isn't lost.