(20140831) How overlooking the one single threat from the opponent proved fatal

...in my own game. Here is how:

I can't explain it. :) Maybe this happened because it was my first tournament in 4 months and I had not really been used to the competitive athmosphere yet.
While the opponent was deep in time-trouble (and still with plenty of time, 18 minutes, on the clock for me), I should have stood up from the table and walking around a little I could have thought with a fresh head...
The full point was a very big present from me, whose only luck was that the fatal blunder didn't cost a single FIDE rating point, because White had no rating yet. :)