It's likely that the game lagged out due to a small technical error either within your network or the games server for a brief moment.
It's also possible that your game could of perhaps randomly frozen due to an error from your computers web browser or such. Although you shouldn't be so distraught, if you enjoy the game as much as you imply then the loss of some rating should certainly not have you consider quitting.
There is more to the game than the points, most people don't even bother about their rating, only those who are very competitive do and although I understand liking the points on here they aren't exactly required to enjoy the game.
If i were you, i would take it on the chin and just continue to play the game you enjoy. Don't quit over the loss of points Buddy, it's not something to get too worked up over. Just continue playing and have fun, rating isn't everything :).
Take advice from a fellow Veteran of this community website, having been here almost 13 years like yourself Please do not quit over a few points. Do what I did, continue to play and enjoy these games whilst you value them worthy of your time.
I understand your frustration though, believe me. Nobody likes to lose over a technical error that could have most likely been prevented..sadly some things are left without a solution but to get back up and keep on playing the game you enjoy and look past these issues that will hopefully very rarely occur.
I'm sorry that you're considering quitting over it, but obviously it's your choice to do so which is fully understandable.
I hope you have a pleasant time if you continue to remain here and play the games,
Kind regards, Jeff.