You can download Firefox 3.6 from http://www.firefox.com/all-older.html

"Thank you for contacting DigitalPersona. There will be no update releases for DigitalPersona Personal in the future. There will be no updates for Firefox 4 nor Internet Explorer 9. IF they work they work, if they do not work with DPPersonal, then you will have to decide to either keep DPPersonal and forgo Firefox 4 or IE 9, or vice versa. DigitalPersona is leaving the consumer market and is focusing on business applications. In fact, DigitalPersona Personal will not longer be supported after Mid-April of this year. We apologize for any inconvenience this might cause. Sincerely, Tech Team "

You could try this extension.
https://addons.mozilla.org/en-US/firefox/addon/fingerfox-se/

The New Version Of Firefox Is A Shell Of The Old ! Over half of my bookmarks "WOULD NOT" connect and what did connect was a display of TRASH ! What a mess ! Sorry Mozzilla ! But You FAILED BADLY ! Whoever sold you on this New Version Should Be Fired ! PERIOD ! Faster ? NOT ! It's far slower & a complete MESS ! Love Firefox ! But this new version is a flat out Failure !

I FINALLY Got The Older Version Back After Several Attempts ! Here Is How ! And NO Problems At All : You can download the Older Version We ALL Love At:

" SoftSonic " Downloads.

It totally Removed The New Trash Version & Gave Me Back My Dignity !!!! Everything Plus ALL AddOns Are GREAT ! Way Better & Far Faster & Accurate !