It is difficult to replicate the issue and it is not always reproduced. When using the splitter between columns[1] and columns[2]  to resize column[1] I found out that releasing the mouse button doesn't cause the splitter to be released, even when clicking on the grid. It seems to work ok once or twice but once it fails then keeps failing.

Workaround:
        private void radVirtualGrid1_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == System.Windows.Forms.MouseButtons.Left)
            {
                this.radVirtualGrid1.Cursor = Cursors.Default;
            }
        }