Portal 2 freezes when trying to use the chamber building tool

[AssFantastic]

Title is pretty much my problem. It repeats the same quarter-second sound over and over again and I can't view, edit or make new test chambers. Can somebody help? Verifying the game's cache integrity does nothing, by the way.

[AssFantastic]

Bump? I know it's not a thing to do but i really need help!

[Malvodion]

This happend to me aswell. It's not exclusive to the PeTI, but also to the single and co-op queue lists.
I never managed to fix it. It's the main reason I stopped playing the game (I used to play a few custom test chambers once every few days. This happend on last year's christmas. It was sad day.).
It happend without any reason whatsoever. I didn't add any new maps, I didn't remove any, I didn't add nor remove any mods. One day it simply stopped working.

The game "works" for one map sometimes every blue moon, but you have to try opening the game several time until it works. Don't switch maps in the queue or i'll freeze (you can load the map and then skip the chambers until you get to the one you want to play, or you can unsubcribe to the ones you don't want to play.).