[Moderated – watch your language]
Disconnection and stalling

It sounds like you took too long to make your first move. Don't worry about it. Nothing will happen if you only do it occasionaly by accident. If you make a habit of it you will lose the ability to abort games and have to wait 5 minutes in between games. These restrictions are lifted when you have played more games fairly.
You can read the fair play policy here,
http://support.chess.com/Knowledgebase/Article/View/171/0/fair-play-policy

I just wanted to add that taking a while to move is not considered unfair. It is to stop people from aborting games by waiting for the server to do it for them.
Thank you all for your "tips". I must say that I do not "wait" for the server to do it for me. The "server" can be anything - my modem? the opponent's modem? the telecommunications network? an electrical fault?
Still it has shed some light on "disconnection and stalling". I can see the "spirit of the law" which sometimes unfortunately fails.

The server means chess.com's server. Players get 15-20 seconds to make their first move, otherwise the server automatically aborts the game. It may have happened that the connection between you and the server was slow and the game was aborted before you got to know it was your move.
I think the fair play policy works quite well because it only really affects people who repeatedly break it.
I have not stalled or disconnected wilfully. "Game aborted by the server" - Yet I was told I did not follow the Fair Play Policy. What is 'fair' - you tell me.