One of the workstations within our office is displaying some strange behaviour. Unfortunately, it belongs to a senior member of staff and so I cannot ignore the problem. Randomly, when accessing a website using Internet Explorer 9, he gets a page not found error. If he tries again then the page will usually display as expected. It only happens in IE and everything works fine in Chrome or Firefox. Unfortunately, he won't accept the logic of using these browsers instead and doesn't understand why he should be having these problems.
The main cause of his irritation is that he gets an email from an ISP that displays emails that they classify as SPAM messages. He has the option to click on a link to display the message if he so wishes. In IE, this will work 80% of the time and then suddenly he will click on one of the links and it will seem to pause before displaying the "page not found" error. As I stated earlier, this behaviour doesn't happen with another browser.
I have reset IE and disabled all add ons but this doesn't make a difference. I have also run a malwarebytes and ESET scan on his system and both have found nothing.
Does anybody have any bright ideas?