Conditionally Locking A Range

Hi All,

This problem is well beyond my Excel knowledge so I'd appreciate any help you guys can give me. Please have a look at the attached file which illustrates what I need to achieve.

So, we basically have the building blocks of an Action Tracker spreadsheet that needs to prevent users doing certain things. F1 and F2, which are Data Validated as a list over N5 to N6 allows a user to choose if they want to allocate a Categpory or Owner to a stated Action (B5:B10). The default to both is "Yes' which allows the User to select a Category from a Data Validated list over L5 to L10 and an Owner from a Data Validated list over M5 to M10.

If the User selects 'No' to either F1 or F2, is it possible to lock ranges C5:C10 and D5:D10 respectivley so when the sheet is protected, that they cannot make a choice from the drop down lists under Category or Owner?

Many thanks in advance

If I knew how to I would. I'm a bit of a cross newbie-intermediate Excel user.