quiz slides random format change?

Judy is part right when she says "there may be no way to completely avoid that sort of thing--especially when importing slides and working with extra-large files" - there is no way to completely avoid that sort of thing. 

But as I read your post, you are copying and pasting your slides, and c&p almost always messes up in SL. Importing slides almost always works. Even better, exit SL, copy the .story file, open the copy in SL, and delete the unneeded parts.