how to disable a particular CELL in matrix?????

Hi All,

I have a doubt regarding the matrix.In my matrix the first column is a combobox it has a,b,c items....so if i select 'a' the remaining 'b' & 'c' columns should get disabled....previously iam able to disable the 'b' & 'c' columns but it's disabling the total 'b & 'c' columns in my matrix.....i just want to disable the particular cell based on the combobox selection....can we disable a particular cell in matrix.....

regards,

shangai.