in my experience, this happens only when you have poor upload speed - for example, if you play while some torrent is working in background.
Unjustly lose game!
Funny thing, server adds time ONLY to opponents.
And NEVER to us !
:) Your opponent is thinking exactly the same thing
What you (most probably) deliberately try not to understand is, that the actual time that user has isn't 79 seconds, but 60, and the 19 seconds is lost through lag. Lag adjustment is simply trying to make things fair, so that every user has those 60 seconds of thinking. It's not a psychopathic conspiracy especially engineered for us poor chess.com users.
More generalities. I am sure you can not explain in detail how and why a clock stopped at 1.21 is restarted at 1.40 after reconnection is established from a temporary disconnection.
Uh... I just did dude... but go ahead... still be mad and I still be cool, again, if you clearly dislike this there is plenty of OTB action out there :)
I had the problem too. I had to clean up some Java regestry errors and other problems with my machine. Since then I haven't had this problem. Hopefully that's the solution.
Many comments in this thread assume that what I see in my browser is not what the server or my opponent sees. This is simply not correct. The server may "notice" a temporary disconnection when my opponent's clock is at 1:40, for example, then 19 seconds later my opponent reconnects. The server does not notify my browser of any problems until it resets the opponent's clock to the time at the temporary disconnection. So it looks to me and my browser like my opponent got 19 seconds added back to his clock, when in fact my opponent was simply disconnected for 19 seconds.
that time you see is virtual only on your machine, your opponent dosent see it the same way you do
Wrong. 1.21 is Live Chess server time.
Im not completely sure about this, what I know is the server runs on Java and Java collects data from your local machine and not from the server. But I have been in both ends, sometimes I lag, and others I get guys who are lagging and its always the same it seems to me the others are the ones lagging and not me
ChrisFaltere and IMDeviate: You both need to know that it is not the opponent who got disconnected but the player. And it was the opponent who was waiting till the player made his 10th move that received additional time when the Live Chess server restarted the opponent's clock.
The player (White in Comment #28) who got disconnected for 20 seconds was penalized 20 disconnect seconds plus 3 seconds consumed so that his original time of 1.23 went down to 1.00 after completion of his 10th move.
The opponent who did not disconnect lay idle awaiting White's 10th move.
After White made his move, the Live Chess Server added the 20 seconds of disconnect time to Black's clock when it restarted Black's Clock making the original time from 1.21 to 1.41 (The screen shot shows 1.40 but that is because the clock had already counted down by 1 second) upon restart of Black's clock.
No matter how you do the math, bonus time is bogus.
I know, I know I'm an "unpaid" member but chess.com doesn't seem really motivated towards solving the problem of lag and lag cheating and disconnect cheating.
They'll say "oh that's just the internet" but funny I never have games disconnect or lag badly on FICS and ICC. Not sure where FICS and ICC servers are or who the provider is, but they do seem to have an advantage over chess.com's live chess server farm.
I don't see many disconnects on chess.com, but I do see lots of lag issues and it's true some of that is "just the internet." But some of it is not "just the internet."
Do you use a web based application on FICS or ICC? :)
Chess is played on the board...
If one plays good moves on the board, he/she does not need to worry too much about inconsequential "technicalties" of 10-20 extra seconds...
Same is true for OTB games (e.g. blitz), one should not try to win "on time"...
If one's position is already lost, resignation is respectable --even when opponent may have only 1-2 seconds left...
I agree that you should resign where your opponent is clearly winning regardless of time constraints
On the "neverending"
discussions here, I think it is very very fair to penalize the player who was disconnected (for whatever reasons, since internet cannot be proven to Chess.com or others).
I do not know if the "bonus" added to opponent's time is for that purpose (bonus) or for technical (i.e. servers) reasons. In any event, it is definitely NOT unfair.
Contrary to what have been commented here, both FIDE and USCF Rules DO allow arbiters/TDs to make adjustments to the clocks if deemed necessary. For example (as an analogy to the case discussed here), in blitz/"time trouble", when a player --on his move-- "disrupts" the game by knocking down several pieces on the board OR (worse) knocking the whole board & pieces off the table. Clearly, the player must restore the position "on his time". But arbiters MAY also considered the act (bcs it is difficult to prove if arbiters are not watching) to be disturbing the opponent, and accordingly penalize the player by adding time to opponent (instead of deducting more time from player, who already lost some time for restoring the position on board). That is very very fair.
10 years ago (i.e. dial-up connections), disconnection means a certain automatic loss of game; since reconnection takes "forever." Nowadays, I think we should be happy that reconnection loses only 10-20 seconds.
All that said, I do not like to play "Live Chess" any more for exactly these disconnections/reconnections surprises; especially when I had forced mate-in-2 or mate-in-3 and suddenly the "trying to reconnect..." dialogue appeared !! 
I agree that you should resign where your opponent is clearly winning regardless of time constraints
Sorry but winning on time is a win. Those pesky rules, ya know.
Clock management is part of the game, if you can't manage your clock you deserve to lose. Goes like this, both sides agree to a time control. If one player spends more time on a series of moves and finds better moves they may well have winning chances over the board but if they've used all their time too bad.
That said there are some situations where it's still appropriate to resign. For example if you're dead lost and your opponent has sufficient time and skills to win. Mostly this would be a correspondence chess game or something played on chess.com at correspondence chess type long long long time controls. Maybe even at an OTB tournament.
But in a blitz game where the stronger side has only a few seconds left? Nope. Play it out and make the other side prove it.
true
Funny thing, server adds time ONLY to opponents.
And NEVER to us !