Explorer performance slowdown

Is anyone aware of a problem with having a directory with
video files (144 to be exact) that would cause the
following:

Nothing else running & CPU at around 7%
Open explorer window (My Documents\My videos) and the
system screeches to a halt and CPU is between 22% and
75%. After a couple hours it comes back to normal.

I have tried this various times and cannot identify a
problem. We are running XP with most of the current
patches applied.

brian