This is in planning for upgrade to J!3. I have found no workable solutions here or elsewhere on the web.
CiviCRM 4.6.4
Joomla 2.5.28
MySQL 5.5.38-1~dotdeb.0
Apache 2.2.16
PHP 5.3.29-1~dotdeb.0
Debian Squeeze 6
Linux 2.6.32-5-amd64
On all virtual hosts before I updated CiviCRM (4.4.x and 3.5.x) the Dashboard shows up but the Ajax "Loading..." widget just keeps spinning and freezes the whole GUI. If I click on another CiviCRM link and restart Apache, it will go to that page and I can navigate around but going back to the Dashboard locks it up again. I then updated both instances to 4.6.4 to the same result. I've disabled all other third party extensions to no avail.
I get no unusual errors in Firebug. Under Net, just a bunch of GET 304 reports for a lot of CiviCRM jQuery and other Javascript libraries.
Turning on Debugging with backtrace produces no output. Clean page.
Any help would be greatly appreciated. Thanks in advance.