How do I design an admin window for cascading dropdown data?

I am designing a window in a desktop app that allows the user to drill down to a specific problem using five cascading dropdowns. The first is general (eg harware or software), the second slightly more specific and related to the selection in the first and so on.

When they have selected something in all five dropdowns, a "Solution" dropdown will be enabled, and will be populated with solutions relevant to the settings of the five problem dropdowns. See the mockup below...

That bit isn't a problem. However, I need to work out how to design an admin window for the admin people to maintain the data. They need to be able to add, edit or delete data at any level, and set the appropriate solution for the final dropdown.

Anyone any suggestions as to the best way to do this?

Don't know if it's relevant, but this will be a traditional Windows (as in Microsoft Windows) desktop app.

Thanks