I recently played with Blender 2.5 Alpha0 on a Windows 2000 machine which has set it's panel at the top of the screen. When Blender is set to render into a seperate render window, this window sometimes creeps underneath the Windows panel, making it a bit of a hassle to move it back. The render window doesn't seem to respect the Windows panel's screen space in this case.

A later Graphicall build, revision 25269, also shows the same behaviour.

Thanks,
Sanne