Make sure your graphics hardware is up to snuff for using this kind of software. You might want to have a decent dedicated graphics card. Unfortunately, some on-board solution, especially the kind that can be found in a lot of laptops, doesn't really work out very well for this kind of multimedia stuff. Make sure to update your graphics driver. It's hard to pinpoint whether this is a technical issue or just a matter of program settings. If it's really just some program elements missing in the "Edit" section, open the "Window" menu and make sure the different components (media pool, program monitor, project) are enabled or click on the appropriate option to bring them up in the main editing screen again. They might have been accidentally disabled.
If the problem is actually that the program is somehow hanging or crashing when switching to edit mode and you don't have any control over it any longer, please try this: Run the program, go to the "Help" menu and use the "Reset program settings to defaults" command that you will find there.