\system32\hal.dll missing or corrupt file (windows xp)?

we are trying to reinstall windows xp but when we put our disk in a message pops up saying that it is unable to open or load windows because \system32\hal.dll is either missing or corrupt and that we must download that file but im not sure how to do that.We had to reinstall about a month or so ago and it worked but this time it wont.I dont think the cd is damaged its a pretty new cd just bought in december 2005.Can u plz help and give me some advice on what i need to do.Would appreciate it very much.thanks