ITunes won't Install

Hello,

When I install iTunes it gets near the end and says "There is a problem with this Windows Installer Package. A programme required for this install to complete could not be run". I've tried looking on Apples website for solutions but haven't found anything. This is on the latest version of iTunes 9.2.1. I have tried many times Installing it and uninstalling if I press of it carries on installing but when I come to open iTunes by clicking on the icon it says configuring to Windows and when that is done it does nothing and if I keep trying it just keeps doing it over and over again. Any help on how to get it to work properly? (: Please i need music badly! Many thanks, Owen.