HELP: GIF question

[Diane Madrigal]

I have a GIF image that seems to change its appearance when I insert it in an HTML page.  If I view it in a browser (Netscape 3) by itself, the colors are clear. But when I use it in a web page, they take on a sort of patterned look. Can someone tell me why this happens, and whether I can do anything about it? (I didn't create the image, so any significant changes there are probably not an option.)

Here are the URLs:

http://www.nysl.nysed.gov/gis/temp/foursm.gif
http://www.nysl.nysed.gov/gis/temp/dostest.htm

Thanks!

Diane Madrigal
New York State Library