weird form Error

this is the error :

Error   1          Cannot implicitly convert type 'string' to 'System.Windows.Forms.DataGridViewTextBoxColumn'           C:\Users\E574129\documents\visual studio 2010\Projects\OPC-UA Server1\OPC-UA Server1\Form1.Designer.cs     223      25       OPC-UA Server1

this is the line of code with the error :

 this.Name = "Form1";

it is in  Form1.Designer.cs

I have never seen this error before

so I am lost.