With your image issues, are you on Vista or Windows 7? If so, the notes at the bottom of this post may apply to you. If you've checked that, another thing you might do is verify that the name of the file is *exactly* what it should be (missing letters, capitalization and spaces instead of underscores (if applicable) can all make your changes not appear). Sometimes programs make png files PNG files, and that could be causing the issue as well.

Good luck!