Mapserver Displays Incorrect Image, Help!

[David Horowitz]

I am experiencing a strange bug with mapserver, hoping someone can
help.  The application uses the rosa applet.  Occasionally after zooming
or paning, mapserver displays an image already generated from a previous
session instead of generating the appropriate new image.  The
application expriencing the problem is running on a Redhat 9 system.
Oddly, a mapserver installation running an identical application seems
to work perfectly fine on a Windows machine.  Any ideas?

The only thing I can think of is that mapserver either isn't generating
a unique identifier for each image or generates a unique identifier but
selects the incorrect identifier to display.  Are these possiblilites?

If it helps, the link to the application is:
http://www.cattlab.umd.edu/region.  Thank you.