When i play garry’s mod it randomly minimizes constantly maybe every 4 minutes, then maybe after the 8th time i get a disconnected, and my internet just random switches off and need to re-connect…
What viruscanner/aditional firewall are you using. It sounds like your visuscanner doesn’t like GMOD.
Also have you tried re-installing gmod?
In addition to the antivirus tip, here’s my two cents.
I personally have had a problem with a mysteriously broken program that would attempt to appear and immediately disappear, effectively minimizing my games and anything fullscreen.
Go into your msconfig (System Boot Configuration) and uncheck anything in the Services and Startup tabs that you know you don’t need booting with your system. Restart, and then see if that helps.