Leo says that just happens when Internet Explorer is crashing. The web is an unpredictable place and bad code can be causing it to crash. Leo advises using the most recent version for her operating system, which would be Internet Explorer 8. She should make sure to run Windows Update regularly. In fact, set it to automatic so she doesn't have to worry about it. Also, once a month Leslie should be running Microsoft's Malicious Software Removal Tool. Click Start - Run - type MRT and hit enter.
Another issue could be that Leslie has installed a toolbar or extension that's poorly written, making the browser crash.
She could also download Google Chrome, which Leo likes better than Internet Explorer.