IE8 Issue - Joomla 2.5 / Kunena

Hi I have a small issue with IE8. When i test site in IE9 it works fine, when i use IE9 but switch to IE8 mode it works fine. 1. BUT when i use XP with IE8 the website firstly runs very slowly...takes about 35seconds to load. 2. User cant create or log into when using IE 8 with XP. Need someone to fix this issue for me. Website works well in all browsers except IE8. * Joomla 2.5.4 and Kunena Forums