I'm on XP and have no problem at all. Therefore I would suggest that the problem is with your installation of XP, or perhaps Internet Explorer. Try using Firefox and see if that runs ok. If not check you installed the motherboard drivers - reinstall them if necessary. And if that fails try a repair of XP and see what that does.
I must admit I'm at a bit of a loss as to why this should only happen on the PCA website. Perhaps someone else will have an explanation of this.