All default tools gone

This just started to happen randomly since 3 days ago.
If I upload an addon to the addons folder, all default tools disappears from the Q menu, and console spams of “can’t derive of non existant base_gmodentity!”

By removing the addon, it works again.
By putting them inside their folders, it also works(garrysmod/models/ etc)

What can cause this?

[editline]26th October 2013[/editline]

Someone rated me funny, so to clarify that I’m not doing something stupid:
An example is uploading the entire “PlayX” folder into my garrysmod/addons folder.
Or, “TDMCars - Bugatti”. Same result.

I ran into this problem a while back and with a lot of trial and error I noticed that entities would still exist server side but be non existent on the client, my best guess is you are hitting a limit ( 2048 if I recall ) for the number of client side scripts the server will send, the only fix I know of right now is limiting the number of client side scripts being sent… removing addons you don’t need.

There are several threads like this of people who have ran into similar issues, you could also try compressing many scripts into one… but I’m not sure if its worth the effort.