To reproduce:
- Add PageView to a form and set its Dock property to fill.
- Add single page and set its AutoScroll property to true.
- Add some controls and make sure that a scrollbar will appear.
- Start the application and scroll to the bottom.
- Maximize the form. You will notice that the scrollbar position is wrong.

 Workaround:
protected override void WndProc(ref Message m)
{
    if (m.Msg == 0x0112) 
    {
        if (m.WParam == new IntPtr(0xF030)) 
        {           
            this.radPageView1.SelectedPage.AutoScrollPosition = this.radPageView1.AutoScrollPosition;
        }
    }
    base.WndProc(ref m);
}