Game freezes my pc??

My pc Is good like it runs most games fine on max graphics. But for some reason if I tab out onto discord or smthn from val it freezes my whole pc. Like this only happens on val. I can’t turn it off besides if I plug it out. The game runs fine but it’s just if I alr tab so it’s not a massive deal but it’s still annoying. Idk if this makes sense but, someone lmk if u know what’s up