The SuperPreview feature in Microsoft Expression Web 4.0 supports the following web browsers on your computer:
Internet Explorer 9
Mozilla Firefox 3.6
Internet Explorer 8
Mozilla Firefox 3.5 (excluding 3.5.5)
Internet Explorer 7
Mozilla Firefox 3.0
Internet Explorer 6
If you have updated Firefox to a version that is not supported by Expression Web 4.0, you can re-enable Firefox support by installing a previous Firefox version to a different directory.
Also, you can disable the auto-update functionality in Firefox to make sure that Firefox does not auto-update to a newer, unsupported version.
To disable the auto-update functionality in Firefox, follow these steps:
On the Tools menu, click Options.
Click the Update tab.
Click to clear the Firefox check box.
Click OK to apply the changes.