TextBox - Can not drag select text

Question

I'm having an issue on a C# project where when I click on the text box, the cursor always moves to the first position. Text can not be selected by click-dragging across the text either. Double clicking words will select text.

The only event I'm catching on the text box is Textchanged.

Anyone know what could be causing this?

Relevant Code:

// From windows generated code
// 
// txtTankName
// 
this.txtTankName.CausesValidation = false;
this.txtTankName.Location = new System.Drawing.Point(87, 21);
this.txtTankName.Name = "txtTankName";
this.txtTankName.Size = new System.Drawing.Size(252, 20);
this.txtTankName.TabIndex = 21;
this.txtTankName.TextChanged += new System.EventHandler(this.txtTankName_TextChanged);


// Event function
private void txtTankName_TextChanged(object sender, EventArgs e)
{
_ThisTank.Name = txtTankName.Text;
}