You have few options:
1- Buy a new Computer (Error will still happen)
2- Increase RAM size. (Error will still happen)
3- Close all background processes. (Error will still happen)
4- Wait for Unity to Fix it. (Error may still happen)
5- Keep playing and ignore the error. (Error will still happen)
6- Use a different browser. (Error will still happen)
7- Use Unity Web Player (Error will not happen)
