Weird Gmod Problem

So recently I have been playing gmod. And about 5 minutes into my game, I get a very strange problem. My game lags/freezes for a moment, then goes to my desktop as if it minimized. But I can’t click on anything, and I can hear movement and what is going on within the server, chat being submitted, people walking, etc. I hit my windows button, and then it shows I minimized it and I can do stuff now. I click the icon on my task bar to bring it back up, and you have the outline go to the screen as if you did bring it back up. But it just shows my desktop, and I can’t really click again. And of course, again I can hear what is going on within my games, as if I was still in it and it is just showing my desktop. I then have to pull up my task manager and close it out.

I have a brand new computer and I was playing Metro 2033 RP, I had all the content etc. What’s going on someone please help.