We also have the same problem running windows xp with multimedia players like Windows Media Player or our digital signage software player, that use the DirectShow interface. eg. with the VLC player, the problem does not persist. If we run the Intel display driver in landscape (normal) mode, the consuming paged pool memory per day is about 110kb. If we run the display driver in portrait (-90 degrees) mode, the consuming paged pool memory per day is about 1.7Mb. This problem also persists with different Intel Graphic Chipsets and is definitely a driver problem.
By now, we can not change to Win7 and need to stay on WinXP.