It usually has to do with a setting in Internet Explorer.

Have him click:

Tools

Internet Options

Then click the button under "Temporary Internet Files" that says "Settings"

There should be some selections under "Check for newer versions of stored pages".

I have mine set on "Automatically".

Sometimes when I'm working on a page, I get the old version, and I have to just close Internet Explorer, and then open it again and the new page loads.