screen goes dark after loading?

this has happened to me a lot. i keep trying to play gmod, itl load up, but when loading it stops and goes blank. this usually happens when i add maps or addons. i just want to know what i might be doing wrong.

p.s. sometimes i add addons but they dont show up in gmod(such as elite strider or aputure science fighters) plz help.

Just hit Ctrl + Tab and it’s fixed.
I think everyone is getting it because I am.