Sounsd like what happened to the tournament is that the number of participants dropped below the minimum threshhold so the whole tournament was cancelled: it happens because people drop out of a tournament as soon as they lose more games than they expect and can't be bothered playing out the remaining games. It's a reasonable policy - if the players have gone, you can't force them to play the remaining games, and if you don't have enough to proceed with the remaining rounds, then there's not much point, really, is there?
Other people can't make your screen lock, and especially can't make it lock when you're in a supposedly winning position on this web site. It's much more likely to be either some other virus that you've picked up that is affecting all of your PC operations, or connectivity problems that look like you're hanging, when what's really happening is you're waiting on the server connection.
In neither case are there any chess.com "policies" involved, nor are they "unfair". So don't expect chess.com to be able to "help" you with either of things in the forseeable future.
I JUST COMPLETED 10 MIN RAPID GAME TORNUMANENT
I DID LOOSE EVEN SINGLE MATCH AGAINST ANYONE
YET RESULT WAS DECLARED NULL HOW IS THIS POSSIBLE
MY LAST GAME WAS AGAINST I WANT SOME ANSWER
ALSO WHEN EVER I WAS IN WINNING POSTION THESE HACKERS MAKE MY COMPUTER SCREEN LOCK SO THAT I WONT FINISH MY MOVE PLEASE I REQUEST STAFF TO LOOK IN TO MATTER AND GIVE FAIR DESCSION THANK YOU