Tried swapping out game.qvm, ui.qvm (from base\vm, vms-1.1.0.pk3, and %appdata%\Tremulous\base) while also swapping tremulous.exe (TF/TJW/stock).
Everything but the stock client causes Trem to crash with the same effects as before.
Updating to TF 0.99r3 doesn't do anything either.