You need some sort of browser in order to be able to access A2K or anything else on the Internet. That is what Internet Explorer is. Unless you have an alternative, say, Opera, Firefox, AOL's own proprietary lousy browser or Netscape, you cannot get into A2K.
So keep IE unless you have an alternative.
As for "deleting MSN", I wish I knew what you meant. Is it a link to MSN? If so, then by all means can it, although I bet it's not the source of your problem. Is it a toolbar? If so, you can probably delete it. Is it being used as a browser? Then see the IE paragraph, above. Is it just Hotmail? Then it's a link and you can delete it, but dollars to donuts it's not the problem.
Please try to describe the problem you're having. Post pictures if you can. Is it slow? A weird-looking site? Popups? A redirection when you type in one web address you end up at another? A change in your home page that you didn't authorize?
You have got to give more specific information, otherwise it's next to impossible to help you. Okay?