To solve the Basement Door not opening even with Police Officer Douchebag at your side, do this fix from user CalicoJack as he mentioned it in the discussions.
The PhysX config fix
Option 1:
Just disable the PhysX and activate multithreading support in the config.
No need for unofficial patches.
The only physX physics are the Dudes coat. no big deal, you’ll get fewer crashes by disabling it.
Here:
disable the games inclusion of “PhysX” and enable multithreading by adding some command lines in the autoexec.cfg located here: “<path-to-game>/p3/cfg/”
open with texteditor and add these lines:
physx_enabled 0
r_threaded_particles 1
r_threaded_renderables 1
snd_mix_async 1
Option 2:
Are you on a pacifist run? Try not to use Tazer and use Fart Gun instead. If you are not on pacifist try to restart the level from autosave. If it won’t help – only starting a previous mission may help.
