Flash doesn't behave the same in different browsers !?

I’m experiencing some weird issues…

First, after hours of coding and adding to a microsite Im working on, I had a look at it on IE, only to realise that once embedded, the flash file doesn’t work !?

Is it to be expected to have inconsistencies between browsers, with flash !?
I’m not using anything crazy, here… Just some XML loading for some sort of image gallery/ image menu.

Anyone knows what this is all about ?