On two customers machines with Windows 7 and Firefox 26 happens following:
At the webpage I have a div container which display the several different content, depending on the menu item choosed. Only with 2 contents there is a wrong display: Below the container there is a single line of content text which should not be visible (outside of container). This line disappears after some seconds.
I can't reproduce this on Mac, on Windows XP and Windows7, where the Windows machines are running in VMware. Neither a friend of mine can reproduce this. On the clients machine the wrong display is not shown on IE. This machine has a ATI Mobility Radeon HD3400 graphics card.
On all other menu items the wrong display doesn't appear.
Re: temporary displays content outside of container
I got the response from the customer. Disable hardware acceleration fixed this issue.