Switching to fullscreen in MyTV --> Exeption

[Seiborque]

Windows Version: Windows XP SP2
CPU Type: AMD Athlon64 3000+ Venice
Memory: 1 GB Corsair ValueRam
Motherboard: Asus a8n-e
Motherboard Chipset:
Motherboard Bios:
Video Card: X Geforce 6800GT
Video Card Driver: Forceware 81.94
Sound Card: Realtek AC97 onboard
Sound Card AC3:
Sound Card Driver: n/a
1. TV Card: Hauppauge WinTv Nova S-plus
1. TV Card Type: DVB-S
1. TV Card Driver: 2.3.237
Video Render Type: VMR9
Video Codec: Mepg2dec
Audio Codec: Mpeg/DTS/AC3
Satelite/CableTV Provider: Astra 19.2° E

Hi,

I'm experiecing a problem with going to fullscreen when in myTv and watching a channel already. Then using ALT+Enter or clicking on Fullscreen leads to an
exeption.
What's amusing: Sound is still functioning.
As I have found out, this expcetion isn't always triggered, but I can't tell when it appears.
When switching to fullscreen in main menu, and then going to MyTV, anything is fine.
But changing then back to windowed mode isn't possible either --> same exeption.

I hope someone can give a tip, how to solve this prob.

PS: Here's an excerp of the exception log:

************** Exception Text **************
Error in the application.
-2005530516 (D3DERR_INVALIDCALL)
at Microsoft.DirectX.Direct3D.Device.Reset(PresentPar ameters[] presentationParameters)
at Microsoft.DirectX.Direct3D.Device.OnParentResized( Object sender, EventArgs e)
at System.Windows.Forms.Control.OnResize(EventArgs e)
at System.Windows.Forms.Form.OnResize(EventArgs e)
at MediaPortal.D3DApp.OnResize(EventArgs e)
at MediaPortal.D3DApp.OnSizeChanged(EventArgs e)
at System.Windows.Forms.Control.UpdateBounds(Int32 x, Int32 y, Int32 width, Int32 height, Int32 clientWidth, Int32 clientHeight)
at System.Windows.Forms.Control.UpdateBounds()
at System.Windows.Forms.Control.WmWindowPosChanged(Me ssage& m)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ScrollableControl.WndProc(Mes sage& m)
at System.Windows.Forms.ContainerControl.WndProc(Mess age& m)
at System.Windows.Forms.Form.WndProc(Message& m)
at MediaPortalApp.WndProc(Message& msg)
at System.Windows.Forms.Control.ControlNativeWindow.O nMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.W ndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)