So I've confirmed that it's not just my computer that has issues with quicktime playback in vista. If you have vista+firefox+adblock plus(extension)+quicktime, then you likely will not be able to play embedded quicktime videos (either crash browser or get illegal operations). If you disable the adblock plus in the "add ons", it works fine. Now I'm not sure if the problem is with the quicktime plugin or the adblock plus. For now I've disabled adblock plus and installed adblock instead, not as good, but at least it blocks the evil intellitxt with some configuration. Just thought I'd share what I found since I believe this is a common problem. If you want some quicktime to test your playback, go to apple.com/getamac and view some quicktime videos. I'm not sure if this combination always causes this issue, but it did on a new install of vista as well as on my machine. I know xp works fine when using ff+adblock plus to play quicktime. Any comments welcome to further discuss the cause or if you are having the same problem.