Map Editor greyed out

Lately I decided to dive back into MTWI (Gold Edition) for a spin. Then I noticed that the Map Editor was greyed out. That's a real shame as creating new fields of battle is quite fun. I don't understand this. I did get a new videocard (Geforce GT730) but never had a problem with the Map Editor....untill now. Anyone has an Idea? Could the cause be a security download from Microsoft? I'm still running W7 and MTWI works a treat.....except for the Map Editor. Please let me know if you know of a solution.