Control cell entry based on condition

[ujjwalgogoi]

Please help in solving the below problem (I am using Excel 2007):

Cell A1 contains a list of 3 selections: A / B / Both A & B. Initially D10:F11 should be de-activated (with grey fill) restricting data entry and if user tries to enter data into D10:F11, error message should be displayed to select from the list in A1

A. Initial Selection in Cell A1:
(i) If “A” is selected in A1
a. Activate cells D10:F10
b. Cells D11:F11 – Erase any previous data, Restrict new data entry & fill them with grey color. Additionally if user tries to enter data into D11:F11, error message should be displayed to select either “B” OR “Both A & B” from the list in A1

(ii) If “B” is selected in A1
a. Activate cells D11:F11
b. Cells D10:F10 – Erase any previous data , Restrict new data entry & fill them with grey color. Additionally if user tries to enter data into D10:F10, error message should be displayed to select either “A” OR “Both A & B” from the list in A1

(iii) If “Both A & B” is selected in A1
a. Activate cells D10:F11

B. Change in selection in Cell A1:
(i) If selection in A1 is changed from “A” to “B”
a. Cells D10:F10 – Erase any previous data, Restrict new data entry & fill them with grey color. Additionally if user tries to enter data into D10:F10, error message should be displayed to select either “A” OR “Both A & B” from the list in A1
b. Activate cells D11:F11

(ii) If selection in A1 is changed from “B” to “A”
a. Cells D11:F11 – Erase any previous data, Restrict new data entry & fill them with grey color. Additionally if user tries to enter data into D11:F11, error message should be displayed to select either “B” OR “Both A & B” from the list in A1
b. Activate cells D10:F10

(iii) If selection in A1 is changed from “A” to “Both A & B”
a. Cells D10:F10 – Keep it activated with any previously held data
b. Activate D11:F11

(iv) If selection in A1 is changed from “B” to “Both A & B”
a. Cells D11:F11 – Keep it activated with any previously held data
b. Activate D10:F10

(v) If selection in A1 is changed from “Both A & B” to “A”
a. Cells D11:F11 – Erase any previous data, Restrict new data entry & fill them with grey color. Additionally if user tries to enter data into D11:F11, error message should be displayed to select either “B” OR “Both A & B” from the list in A1
b. Cells D10:F10 – Keep it activated with any previously held data

(vi) If selection in A1 is changed from “Both A & B” to “B”
a. Cells D10:F10 – Erase any previous data, Restrict new data entry & fill them with grey color. Additionally if user tries to enter data into D10:F10, error message should be displayed to select either “A” OR “Both A & B” from the list in A1
b. Cells D11:F11 – Keep it activated with any previously held data

(vii) If selection in A1 is DELETED
a. D10:F10 - Erase any previous data, Restrict new data entry & fill them with grey color. Additionally if user tries to enter data into D10:F10, error message should be displayed to select either “A” OR “Both A & B” from the list in A1
b. D11:F11 - Erase any previous data, Restrict new data entry & fill them with grey color. Additionally if user tries to enter data into D11:F11, error message should be displayed to select either “B” OR “Both A & B” from the list in A1