no pop-up window on firefox 12

Hello,

on some menus, in the astaro webinterface, my firefox doesnt open pop-up windows.
I have started firefox in safe-mode, without any add-ons, but no pop-ups.

In the httpd.log only a few lines appear:

-----------
2012:05:09-13:40:17 hostname httpd: ***.***.***.*** - - [09/May/2012:13:40:16 +0200] "POST /index.plx HTTP/1.1" 200 435
2012:05:09-13:40:19 hostname httpd: ***.***.***.*** - - [09/May/2012:13:40:17 +0200] "POST /index.plx HTTP/1.1" 200 458
2012:05:09-13:40:19 hostname httpd: ***.***.***.*** - - [09/May/2012:13:40:19 +0200] "POST /index.plx HTTP/1.1" 200 345
2012:05:09-13:40:20 hostname httpd: ***.***.***.*** - - [09/May/2012:13:40:20 +0200] "POST /index.plx HTTP/1.1" 200 345
-----------

Here are an example where it will not work:

Log & Reporting -> View Log Files -> Search Log Files
Select log file to search: Webfiltering
Search term: facebook
Select time frame: yesterday and today

But it will work on:
Log & Reporting -> View Log Files -> Today's Log Files -> Web Filtering -> Live Log



Astaro ASG120 8.302
Firefox 12 on Windows 7