Fortnite: screen freezes?

I have an ongoing problem. Whenever I play the game Fortnite on my PC, a few seconds after the start of the game, the picture just stands frozen. After 20 s waiting time that freezes again but then after 5 s it freezes again, etc. I also have a Geforce graphics card. But even if I play on the lowest graphics this problem is present. For other games, like Overwatch, this is not the case

Use a hair dryer then you freeze