When the client connects it gets booted with a ZenTreesplosions.pbo conflict.. The Server doesn't see it, the client doe's!

Deleting ZenTreesplosions.pbo client side fixes the issue... I'm guessing the PBO is not linked in to the server so it doesn't load or know it exists.

Deleting from the client and away it goe's.

Terry Lava believes the server is not loading the pbo because it was changed after it was signed.

Hoping this is a simple fix for Zen, but failing that he does allow repacking, so you can remove it and run your own... But as always, we always prefer the real thing over a custom watered down version.