software updates keep on showing the same updates.

I had a kernel crash, that repeated some times, so I read that I should disconnect all external drives and install all the updates available, so I went to softer updates, so the computer checked for all the updates available, and clicked on instal, so my imac just restarts and nothing happen, i go to the software updates, and the same updates are there....and I keep on trying this, with no success, anyone knows whats going on?