sp2 = no more hidden divs?

i'm working on a client's website using hidden divs for navigation. when testing in firefox, it works perfectly. however, when i try it with internet explorer, the information bar pops up and whines at me. i can allow the divs to work, but only if i tell the information bar to go away.

"lolz why u r using internet explorer! fiyar foks rulez!"

yes, yes it does. however, i need to make this site work for the vast majority of people. this has never happened on my system at home since i don't use sp2, but more and more people are upgrading. is this just because i'm viewing the file locally instead of on a website or does this happen all the time under sp2?