iexplorer error

One of the cable modem techs from my area brought one of their customer's pcs to me because he couldn't fix it, and he is pretty sharp. When a different tech installed the nic, all of a sudden you cannot use IE or netscape (he installed that after to see if it would work when IE didn't).
when you try to open IE (ver 5.1)-updated to 5.5, didn't help - it says iexplorer.exe caused an error in unknown
I looked it up at ms but no answer I saw seemed appropriate. I tried taking out all the network clients, adapter, protocols, etc and reinstalling them, nothing (dial-up also gives the error). I am thinking I will probably have to do a full restore (it's a 2 yr old DELL - win98)unless someone has an answer, nothing in my mental "fix" list has made any difference, I even tried that win98fix, windoctor, pretty much anything I could think of. Oh, he also tried reinstalling OS already.
He has wasted so much time and they are sick of it, he said the cable co would even by a new pc if necessary <IMG SRC="smilies/rolleyes.gif" border="0">

Just a thought have you scanned for a virus? I've seen them do some pretty weird things and they don't always do what they are suppose to, sso....

Just an Idea

GLSmith

yeah actually that was one of my first thought but they are running up-to-date NAV
thanx tho <IMG SRC="smilies/smile.gif" border="0">