OK, thanks for posting back the specs for your MacBook Air.
Normally, software updates are benign and do not cause problems. It may have been coincidental with another problem your MBA was having. Anyway, let's try this:
Boot your MacBook Air to its recovery partition. Reboot and hold down the command plus the r key. The machine should boot to the recovery partition. It may take a few minutes to do so. Once in recovery, choose utilities, and then select Disk Utility. Run verify and repair for the hard drive. Let us know the results.