alright, i think i figured it out - thanks to wikipedia:
http://en.wikipedia.org/wiki/XMLHttpRequest - (who btw want all of the instructional stuff on the page moved out)
IE (at least) is caching the response, because my URL is not changing. so it never makes that second call since it thinks the URL is the exact same.
there were many workarounds on the page for this - apparently the best way is to add the pragma "no-cache" but that didn't work for me. in fact it weirdly messed up my form element alignments.
so i had to choose the wasteful way of actually appending a "Math.random()" element to my parameter in the ajax call, so i could fool it into thinking it was a different url. apparently this fills up my cache with all these useless urls, but hey! it fixes my problem for now.
If anybody has any better suggestions, i'd appreciate it.
Thanks again,
Nilesh