Sometimes Safari is not able to fetch the website. It seems to stall. The progress bar is updated to a point, but then does not show further progress. Has anyone seen this? Should I reinstall Safari?

For some reason, when I select a web site for Safari, Safari initially appears to be navigating to the web site: the progress bar fills from left to right indicating progress. Then it just stops showing progress. I have begun restarting my IMAC and have had success. Today, I had to restart the IMAC two times. I have considered reinstalling Safari to remedy the problem. This problem has only just begun, within the last one or two months. I have owned this IMAC for three years and have not experienced ANY problems with its usage. Has anyone experienced problems navigating to a web site with Safari after determining that the Internet Connection is functioning correctly? I should also mention that I have only recenlty (witin the last few days) installed the most recent version of the Operating System (Mountain Lion) thinking that that might solve the problem.