Momentary motion lag

[Froge]

It started today in the Back Hall and never occurred when I was playing before, main game or custom story. Basically there will be random moments where all input freezes and Daniel's current motion continues. So say I have "W" pressed, then when the lag hits, Daniel will keep moving forward as if W is still pressed, and for a couple of seconds both mouse and keyboard input do not respond. When the lag is over, Daniel will jump to the direction my mouse or key currently puts him at.

The times that this happen are frequent but completely random.

I'm using OSX 10.8.4 system, Intel HD 4000 graphics, 2.3 GHZ processor with 8 GB RAM. I'm tempted to blame this problem on the Intel graphics, but this lag has never happened when I played ATDD or AMFP before today. I have Amnesia installed on Steam. I also did not install or download anything today, though I did copy paste an ATDD save file into another section of the computer for later use. Not sure if that's relephant.