Sim2 Expansion Problem

Hey, my sis has bought the sims 2 expansion called university but its not finishing the installation properly. What happens is it installings fine, then after it installs it asks you to insert disk 4 of the original sim2 to update the game,doesn't say why or give you an option to skip so it must be needed. But half way through updating the game it randomly gives an error saying it cannot update the game and it must exit the installation. I'm trying to get on the ea support but their page seems to be down, typical EA. Well if anyones experienced this problem and solved it let me know!. Thank You.

Have you installed any mods?
Did anything change the original EXE?
Have you tried reinstalling the original game before installing the addon?