Please see this FAQ to see if it helps:
My gallery does not show in Firefox or gets cropped to a small height. Why?
A quick fix for this scenario would be to specify your gallery's height as a fixed pixel value rather than as a percentage, e.g.:
simpleviewer.load("sv-container", "100%", "600", "222222", true);
Another thing you can do is to check the validity of the code on your web page with the W3C Markup Validation Service and fix any HTML errors reported. Once the code on your web page validates, it should be rendered with greater predictability and consistency across different browsers.
If you continue to experience difficulties, please post the URL to your gallery so that I can take a look and let me know which browsers it works in and which browsers it does not work in.
SimpleViewer Support Team.