I am using version 2012.2.912.40
I have filled data in each cell by typing, after finishing fill data for one cell I have typed enter key and cursor move to next cell direction go to left to right. In my sample project , you need to fill data for "Group Type,Brand,Stock ID,Unit,Quantity and Price".
After filling data for Price Columns, I have typed enter key and then I have clicked in the Group type Column at the next row of the grid view at that time error occurs.
Please note that I use mouse click one time new row's Group type column to focus and then type data by keyboard.
In my grid view , I have added three multi column combo box for "Group type, Brand and Unit" , I think that error occurs using multi column combo box control more than one in rad grid view.
Please, check this.