Today (almost yesterday, it's very late here) I lost 2 games. OK, I got 0,5 out of possible 2 points. But for me I lost both games, especially because I was winning!
I will show you some of these different types, which can make you upset. I got almost all of them in my two games.
As I already said somewhere, I have problems with computer mouse. What's the difference between correspondence & live? You can rarely see a "mouse-slip" in Online Chess... So, my mouse is really "slippery" mouse. But not outside, but inside.
The contact inside the mouse seems to be broken - when you click on the mouse, sometimes it senses like there were two. In chess, it's embarrasing when you're dragging the piece, it just drops down.
Here is my first example:
I was so upset! Instead of +9, I got -9. I quickly recommended a rematch, because I knew it's not so difficult to compete with 1500. 
I hoped there would be no problems with mouse in the next game. Opponent played Queen's gambit, I was trying to set the Semi-Slav formation, but I faced with hell.
When I was trying to put my knight from g8 to f6, my mouse travelled above the f7-square. And then the mouse dropped the knight (no contact), clicked again (contact again) and dragged the pawn from f7 to f6.
OK, it sounds unbelievable, but it is (believable & true)! 
One thing which annoyed me too was disconnecting. I was disconnected 2 times I think, but my opponent was at least 10 times! All "refresing signs"... Ah, survival rate was high enough!
After some moves, I got advantage again. I recognise it will be easier to win with simplifying the position:
And then: "I'm rushing because I'm in a hurry!"
NO! Never do that. Especially if you have 5 minutes! I offered a free-pawn, and took it too easy.
So, when you're upset:
- Never play an easy endgame
You're upset because of:
- Computer mouse
- Disconnections
Even Garry Kasparov didn't like computer mouse & disconnections! ;)