Win XP, IE won’t pull page, Netscape works fine

I had a cu call in that couldn’t browse. He could ping both domains and
IPs. We checked all his IE settings and they were ok. He was running Win
XP. The XP firewall was already on so we disabled it but he still coudln’t
get online. Just to see, the cu tried to use Netscape and ‘lo and behold he
was able to browse. I had him browse around to make sure he wasn’t pulling
up cache. IE still didn’t work. So, is there any difference in Netscape and
IE that would make a difference?