This is a bit of wisdom that I picked out of a newsgroup several years ago (note the reference to IE4).
As recently as January 2002 the bug still exists in the version of the Web Accessories that can be 
downloaded from MS. And probably still does.


This is a logic bug found originally in the IE4 PowerToys, and successfully
ported (!) to the IE5 Web Accessories (and to the "Images list" from "Web
Developer Accessories" I think, I had to change something there too).

To fix it, use Notepad to open ZOOMIN.HTM (found usually in WINDOWS\WEB\),
end edit it to read both image dimensions before setting any of them:

old contents:
...
h = parentwin.event.srcElement.height * 2;
parentwin.event.srcElement.height = h;
w = parentwin.event.srcElement.width * 2;
parentwin.event.srcElement.width = w;
...

new contents (the 3rd line in the fragment above moved up):
...
h = parentwin.event.srcElement.height * 2;
w = parentwin.event.srcElement.width * 2;
parentwin.event.srcElement.height = h;
parentwin.event.srcElement.width = w;
...

Do the same for ZOOMOUT.HTM.