Random lag and screwing up my computer?

I loaded up Gmod and tried to go on an RP server one day but for some reason it did not load for about ten minutes. Finally it let me in and I was horribly lagging. I figured it was because my settings were high after some ragdoll posing and set them to medium (after spending five minutes trying to traverse the laggy menu’s.) After I did that, it still lagged, I ended up setting everything to the lowest graphics and set my resolution to the smallest and nothing.

I left and tried to play singleplayer, I had the same loading issues. I turned off Gmod and figured I would try again later, I started up some music and it told me all my files were missing. I did the same in VLC media player and it did not start any songs. I checked the folder of the music and it was all there. I sighed and went on the youtube, all videos refused to load. Games played fine though.

I restarted my computer and the sound worked and all, then I tried Gmod again and got the same error, I turned it off and had the same problems as before. I verified Gmod’s files and let it reinstall and nothing has helped.

Is the problem your computer or Garry’s Mod, for me it is a bit unclear. If it doesn’t work uninstall it via Steam, then go to C:\Program files\Steam\Steamapps\Youraccount and remove the garrysmod folder. Then download it again. (Note, the shortcut is what I have, but with something else at “youraccount”

I am pretty sure it is Gmod as no other game is doing this.