I hate to jump in when this is already "resolved", but I've got a similar problem, but with a significant difference. I cannot get the Toolbar/Dashboard to show up in Firefox, but it works fine in IE7.
This started yesterday, after my Firefox 22.214.171.124 did it's latest update. I've cleared cache and cookies, forced refresh, logged out and back in, rebooted computer, rinsed and repeated. Still no Dashboard Toolbar.
Using Windows XP Pro with Service Pack 2.
IE 7.0.5730.11 (works fine, but o please don't leave me using IE instead of Firefox!)
No active software firewall.
Being this is Firefox, this is probably an easy fix, but I'm missing it...