Some complex web sites such as Huffington Post dot com home page load slowly . When they finally load and you attempt to open a tab, several refuse to load. The blue circle just keeps going round and round in a clockwise direction. The prompt box at the lower left of the screen says " Waiting for " or "Reading" or "transferring from" and the name of another web site that apparently contributes to the page. But nothing happens for several minutes. The most common one 'hanging up' is something called pixel.quantserve.com. Multiple attempts "Reloading Tab" do not help. This problem is not present in Internet Explorer itself. Have run AVG anti-virus multiple times and no viruses have been found.