Macbook pro sometimes left clicks are not registered Hi I have a macbook pro 15", primo 2011.

It runs perfect with Mavericks. However recently it has started to get a strange bug from time to time. Some times left clicks on the pad is not working. It happens randomly while I work. It's often happening when I e.g. want to close a window in finder or change/close a tab in safari. 

The issue shows like this: When I for an example hover over the "X" and clicks to close the window, nothing happens. I can try 10 times but nothing works. Right clicking though always seems to work. I have noticed that if I move the pointer a little around (maybe clicking elsewhere) and then back on the "X" again, then it always works fine again.

The issue comes and goes, and I cannot find any pattern, except that it's happening for every 20. left click I'm doing, that the computer seems to not register it.
This happened to me as well, and I just realized that the problem might be because I swapped the hdd drive with other macbook and the when I installed osx the hdd it was in a different macbook, so probably after a reinstall would work.