4
Going by the appearance of the browser window in your screenshot, I'm assuming your friend uses Internet Explorer 5 on Windows 2000. If this is the case, the problem would be related to poor CSS support in IE 5.
If maintaining support for older technology and 800x600 resolution is important to you, you may want to adjust the layout of your blocks so that you only have the left column and the main body column. This should prevent the overlapping effect your friend is experiencing.
Hope this helps.
JMorris
