*Please* Help with loops, arrays, ducument.write.

Hello.
Some of you people are pretty sharp; maybe you can help me with a problem I
can't seem to solve...
The URL below will take you to the page, which (so far) loads a user defined
image and then writes the selected image (or IMap) coordinates to an IFrame
(MSIE only). It also keeps track of the selected coords in an array. The
undo function clears the IFrame and rewrites all but the last array member.
Follow? The problem is, it doesn't work. So I put and alert(...) in the loop
that rewrites the array elements, to monitor the variable values through the
cycling of the loop. Funny thing, now undo() works the way I want it to, but
only with the alert() box interrupting each cycle of the while loop...I
experimented with setTimout loops, etc...No dice.

http://www.usfamily.net/web/kzahler/demo/CoordinateFinder.html

(MSIE only)

click 'load' to load a default image...click on the image several times (to
select coords), then click undo...

Any ideas??? Other ideas? Any help appreciated!!!
Thanks,
KZ