I'm using Quicktime 4.1.2 as you suggested, I don't think it has anything to do with Quicktime because visual effects work fine if JIT compiler is turned off (it's just too slow to do so).
I made a test stack so I'm hoping others can test this and see if it's just a problem with my configuration. I even believe it's just a universal issue with SheepShaver and maybe Windows.
Here is the stack. Just very simple button that goes to the next card, but I put in visual effect dissolve. So if it works, it should dissolve into the next card, not just jump straight to it. Make sure you turn on JIT compiler before testing.
http://www.mediafire.com/?4em4lwpvdgczic4Thanks!