IE8 doesn't work very well on a lot of sites anymore (no HTML 5 support) and it's not very secure (later verions of IE are much more secure). Programs that use the IE WebBrowser control for displaying webpages, which is quite a few, are having the same problems on XP/IE8 systems.

MS will soon not update XP with security updates anymore anyway, basically it's not very secure compared to newer versions anyway so the best thing is to upgrade to Win 7 or 8 which will solve all these problems.