When you watch a video in Windows Vista, video performance may suddenly be reduced. For example, you may notice lost frames or other poor video performance.

This problem occurs if the following conditions are true:

• The system does not support Windows Aero. For example, the computer is running a version of Windows Vista that does not support Windows Aero, such as Windows Vista Home Basic. Or, the video hardware of the computer does not support Windows Aero.
• The video window is partially covered by any of the following Windows elements:
  • Windows Sidebar.
  • The Windows Start menu.
  • A tooltip.
  • A software pointer that has shadows.
  • Any window that has rounded corners or other transparent elements.
  • A window that has shadows.
  • A sprite that has transparency elements or shadows. A sprite is a two-dimensional image or animation. For example, some Gadgets for Windows Sidebar are sprites.

  Video performance decreases only when any of these elements partially cover the video. When the elements no longer partially cover the video, the video plays as expected.

  The poor video performance may be more severe on computers that have slower CPU hardware. Other factors that may affect this problem are the display resolution, the random access memory (RAM), the graphics processing unit, the memory bus, and the drivers.

  For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB932782.