User unable ti access web, but everyone else

Hello,


The laptop used in my house is shared with three users, my mother (whose unexperienced with computers but all too eager to learn, we each have our own user names and passwords, in the past two weeks, i have not used it at all, although I discovered my son had been visiting sites that were less than age appropriate, we dont allow him to have a password for email so when my mother logs into mail she can see his as well as her own, she noticed that one of the messages were subject lined: "hot nude, etc" she claims that she opened the email but she didnt understand why the body of the message had a BLUE BOLD UNDERLINED "WWW. something" I explained that it was a link to a web site.
I have been very cear that sites such as those can possibly corrupt hard drive and email messages that are from unknown senders should not be opened at all!

NOW: I can log on under my user name from the signin screen and navigate around the internet as if there was no prblems at all.
However, when you sign on using her name and attempt to sign onto the internet, a baox pops up that says INTERNET HAS STOPPED WORKING and will freeze up win you attempt to exit internet explorer, what can i do to resove the problem without restoring system to previous date?
I would think if it was a virus or worm that it wouldnt have isolated itself to her username, I want to believe she just did something she had no clue as to what it was.
HELP,
Jackie Rains