Wireshark is a very rich and detailed program. I personally would not think of wireshark as a first go to for diagnosing an intermittent problem to a website or websites. The setup for a filter tends to get rather...interesting. I ran a quick search and found a "easy setup guide" @ http://openmaniak.com/wireshark_filters.php
However, where I would start is connecting directly into your ISP's modem and try again to see if your issues persist. If they do, I would try another web browser, ( chrome, firefox, extc). If still happening, run a full system scan with malwarebytes @ malwarebytes.org
. If no better result, I would check your Host file to see if it have been compromised: http://superuser.com/questions/104792/windows-xp-hosts-file-has-been-tampered-with
. Let us know what you find out.