Your computer needs to meet the minimum system requirements to display the lesson links. This includes the need for a web browser (Internet Explorer 5.5 SP1 or higher). If you are using anything lower than IE 5.5 SP1, you could get a white screen and not see the lesson links. This is needed for the windows to operate properly.
You can download Internet Explorer 6.0 SP1 from the link below.
If this fails to resolve the issue, you should also check the security settings for Internet Explorer. Try changing the settings to Lowest. Make a note of what those settings were before you change them. This way, you a reset them back to those settings after using PC Tutor.