This happens if a particular font (used by the web page) is missing from the system. There are four Verdana in Windows\Fonts folder (Verdana Bold, Verdana Bold Italic, Verdana and Verdana Italic). If those font files are missing in your system, try copying the four Verdana fonts from another computer with XP and installing them on your PC. Then start IE.

Note that this problem can also happen if one or more of your other mainstream fonts (Arial, Tahoma and others) are missing. Here is the list of default fonts that are shipped with Windows XP. Missing fonts can be restored from the Windows CD.

http://windowsxp.mvps.org/IEFAQ.htm#italic

give it a shot