Black rectangle superimposed on screen ?

Sometimes that's your command prompt popping up. If that's what it is, it's a fairly common problem.

ok thanks,  if it's a common problem, how is it resolved ?

I don't know. Depends on why it's happening.

I googled for a solution and found a scam that says to fix it you have to disable your virus protection and run a random program you download from their site, lol.

Whatever you do, don't do silly stuff like that.

ok, thanks.  I had thought the site secure from malware.  But its easy to see some

malicious players and bots are trying hard to ruin the joy of a friendly chess match.

I don't understand why chess.com penalizes players ELO's from trying to avoid people with

bad intent by aborting games with obvious scoundrels.