Cathy is having a problem with Internet Explorer crashing. Leo says that if that's the problem, chances are there's something system wide happening. Leo advises resetting the browser to see if that fixes it. She can go to Tools > Internet Options > Advanced > Reset.
Cathy could also reinstall it, and Microsoft has information on how to do that here.
Another issue could be toolbars. If her antivirus has a tool bar, that may be what's causing it to crash. Leo isn't a fan of antivirus tool bars. But there are other browser options, like Google Chrome, which is sandboxed and has Flash built-in. It's far more secure and up to date.
Leo also suggests uninstalling Norton. She can use their uninstaller. She should rely on Windows Defender instead. She already has it, and it's free.