Symantec need to update their Firefox add-ons so that they are compatible with Firefox 4. They have indicated that for Norton 360 they plan to release an update to Norton 360 to support Firefox 4 in early May - http://us.norton.com/support/kb/web_view.jsp?wv_type=public_web&docurl=20100720113635EN&ln=en_US

Pending the update by Symantec, to downgrade to Firefox 3.6, first uninstall Firefox 4, but do not select the option to "Remove my Firefox personal data". If you select that option it will delete your bookmarks, passwords and other user data.

You can then install the latest version of Firefox 3.6 available from http://www.mozilla.com/en-US/firefox/all-older.html - it will automatically use your current bookmarks, passwords etc.

To avoid possible problems with downgrading, I recommend going to your profile folder and deleting the following files if they exist - extensions.cache, extensions.rdf, extensions.ini, extensions.sqlite and localstore.rdf. Deleting these files will force Firefox to rebuild the list of installed extensions, checking their compatibility, and reset toolbar customizations.

For details of how to find your profile folder see https://support.mozilla.com/kb/Profiles

What problems are you having with Firefox 4?

I may need to go back to 3.6 too. When I loaded version 4 my Roboform tool bar did not transfer. I have posted this as a separate question but have not gotten any help. Version 4 is faster but not if I have to constantly open IE to get my passwords from Roboform. Thanks for any help.

Jim

On a hunch, I went to the Cnet downloads page and found a link to a FF 3.6 download which resolved my problem. This allows my Norton 360 products to operate normally.