Vlk
30
essexboy, you’re right! The Privacy Control settings set to High are indeed causing the conflict.
I’ve found a workaround that works, though.
Set up the proxy settings in Firefox as shown on the following screenshot.
While this is not a definite solution, as a temporary workaround it seems to be working pretty well. 
[i]Edit: maybe I was talking too fast…
The proxy trick doesn’t seem to so reliable work around after all… :-[/i]
Thanks
Vlk