We've managed to fix the start up issues caused by changing depots. Changing the depots caused the new build to not be able to read VPK-files, once again stressing how crucial it is for the update to be released so we can get the game off this broken, old engine!
Our new depots are now sorted and ready for the release of 3.0. We still don't have a release date, but the update is shaping up nicely and will see a release within the scheduled release window. That's all the news about 3.0 for now.
Your game should update automatically and install the fix. If you don't see a pending update, restart Steam.
If you installed the first update but are still getting errors related to "hl2.exe", then note that this has also been fixed and only requires a second update.
Once again, We are sorry for the inconvenience,
Happy Gaming!
- Zombie Panic! Development Team