Barbara- I don'thave much experience with installing programs on XP, although I did buy an XP machine once and did seriously consider buying another today.
But I do get called on and berated when said XP "notebook" machine hangs up in the hands of the "designated user". I have found that when all ese fails, pulling the battery out is not the worst thing I can do.
And speaking of users, is it possible that you are trying to install a program when logged on to XP as other than the designated user who is authorized to install new programs?
Just a thought. Other than that, you might try disabling the CD-ROM read ahead feature in your XP machine, if such a feature still exists in those new-fangled operating systems. I'm hanging in there with Win 98, at least until it is officially retired this week or next.