Hi... So I was just on Safari. I had one youtube video attempting to load. In the background I had 2 tabs open, with news. The only other programs I had open were iTunes on pause and Dictionary. Hardly a big strain... And yet.. my 2012 MBA 13" just went laggy... and laggy... and would not even play the Youtube video. And then as I attempted to type on a second web page, the lag increased. Then, the kiss of death, as I started to type "Activity..." in Spotlight, my Macbook gave up after the letters AC and just froze completely. I closed the lid and the computer stayed on, frozen, crashed. After a 10 minute wait I gave up and forced shutdown by pressing the power button. Now I am back on and everything seems fast and okay again and there is no error message or warning from Mac OS X explaining why Mountain Lion just crashed so horribly while doing basically nothing. So what might be the problem? Miffed and not at all impressed.