Me too. My MacBookAir (mid-2011, 13 inch, i5, 4GB of RAM factory-installed by Apple, running 10.7.5 Lion) started freezing in the last couple of weeks, and the frequency of freezes seems to be increasing. Prior to that, it was a dream machine.
Freezes often happens in Chrome. I keep about 5 tabs open on average. Tonight it froze twice, and once with *only* Chrome open. But it seems like more of a Finder issue, as my cursor still responds to my mouse, but clicking on different window panes does nothing: I remain stuck on the window pane I was in. If I try to launch an app from the dock, a Finder window opens instead of the app opening. If I double click on the app in the Finder window, it opens the app but soon freezes again. CPU is fine, 50% of hard-drive still available, unit is mildly warm but fan not running hot, and no kernel panics in the crash log.
I suspect the Finder.
I just updated all my extra software, including Wacom tablet and Epson printer drivers, as these communicate regularly with the Finder.
WIll give it a 48-hour window to see if this improves anything. WIll also run DiskWarrior in Target Mode tomorrow.