Works for me in ie6, ie8, and FF

[begin rant]
btw, that patronising popup to upgrade ie6 is a sure way to turn away customers.
I suggest you remove it before you go live

Its none of your websites business what browser I use

Its your responsiblity to sell, and if I choose to use ie6 you need to make sure your site works for me
At least until the number of customers using ie6 drops to insignificant numbers
Be aware that a lot of corporates are still using xp and therefore ie6 and their users often are not allowed to "upgrade"
[/end rant]