I'm having similar problems with Valheim. I have my character, Droolius Caesar all set up and ready to start the game. When all of a sudden, CRASH!...Black screen. Then a pop up appears and asks if I want to remain in-game to see if the game will work. Or close the game and leave. (So far, always closing the game. I've tried this 3 times. One good thing, I don't have to re-boot the computer). I am heartbroken, loving everything Valheim has to offer. I've waited a long time to buy this game. I'd rather solve this issue up rather then getting a refund...But on the other hand, I don't want to wait too long with a game that doesn't work.
I'm 'trying' to play on Single Player mode if that helps. I'm really a Lone-Wolf player that plays very few online games.
For the record, my computer is extremely fast with TONS of space to run any game out there. And it has a killer GPU, (Graphics card) that's meant for high-end gaming. So I doubt very much that my computer is to blame for this crashing.