For some reason, my upgrade from Firefox 2.xx to FireFox 3 RC1 was seen unsuccessful to Roboform as it keeps telling me the following message:

This Adapter (6-9-89) supports only Firefox ver. 1.5 to 3.0.*.
You are using Firefox ver. 2.0.0.3. This browser is not supported.
Please upgrade RoboForm Adapter to the latest version or downgrade your browser.
Reason: Cannot register component.

When you checked on Firefox Help/About Mozilla Firefox, make you the fine print reads

Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv:1.9) Gecko/2008051206 Firefox/3.0

and not

Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv:1.9) Gecko/2008051206 Firefox/2.00xx

as roboform will not see it as Firefox 3 RC1.

If after you installed Firefox 3 RC1 and it still appear as 2.00xx, then in order for Roboform to work, you have to uninstall Firefox and install a fresh new Firefox 3 RC1.

Before you uninstall Firefox, you might want to export Bookmark, take note of the Add-ons if necessary though most will be work for Firefox 3.

After reinstall Firefox 3 RC1, reinstall Roboform and it should work.

Firefox 3 Release Candidate 1 is now available for download in more than 45 languages as a public preview release intended for developer testing and community feedback. It includes new features as well as dramatic improvements to performance, memory usage and speed.

Firefox 3 RC1 Release note is available here.

FireFox 3 RC1 Downloads are available here.

P/S: If you are using Roboform, you will not be able to use Roboform till they released Firefox 3 RC1 adapter.