I think this might happen *really* often on computers that are a little older or the browser software hasn't been updated.
I didn't want to say anything, until it happened, because I haven't tinkered with javascript in a long while, but I think that trying to save "temp/session" data between two pages praying that javascript works (window.back()) is gonna be real risky. On many browsers. Too many variables.
So if it does prove risky, we better pass that stuff forward AND backward via FORM POST. That's the way I did it on a ColdFusion board I made...