The only thing i can suggest is turning off all third party plugin and removing any custom JS you have and get a baseline.  Then go from there.  I dont see that comming from  the core, i think its something custom. 

Dave,

Partial success (in uninstalling cloudflare plugin and clearing cache) .

Now it's working in Firefox (great!), but it's still not working in Chrome :(

Maybe you are right about not being something from the core. I'll try to do that (turn off the third party plugins) and see what happens.

GREAT!!!  please keep us posted :)

Hi Dave,

Now, after I have done the changes  (777 recursive permissions set to ow_userfiles, ow_static, ow_smarty/template_c and ow_pluginfiles) it came out another problem, possibly connected with the changes: the users that are unapproved are showing as regular users in "recently active", also in the user photos in Main menu, etc. it seems that they are not blocked anymore (despite their tags are showing to admin) .

OK ross is gone but i will try to help you, i am not that versed in things like a team member is but i will try, just dont hate me if it does not work.  Otherwise you will need to wait for team to return sunday night.  This is their weekend. 

OK, no problem, I'm sure you are good at it and know the system well. Let's go ahead.

OK ill try Geo, whats your domain url i dont see it in prev posts...  Also check your admin settings, page settings and remove any custom head code or tail code in the boxes and save it

Just copy and paste it someone else like notepad to save it if you want to. 

urbnbiz.com

i registered as test, can you email verify me please in admin so i can look around

i just uploaded a photo, it works fine for me check the newsfeed

what is the browser you used

google chrome

chrome still not working for me

now it is working, great!

and what about the issue with the users that are unapproved?

ok please delete my account and reset your browser cache in settings, also reset IE and reboot, also try resetting your dns cache via the command prompt.. 

ipconfig /flushdns

ok what is happening again with them?   remember that google can be very very stubborn when it comes to cache. 

after I have done the changes  (777 recursive permissions set to ow_userfiles, ow_static, ow_smarty/template_c and ow_pluginfiles): the users that are unapproved are showing as regular users in "recently active", also in the user photos in Main menu, etc. it seems that they are not blocked anymore (despite their tags are showing to admin), anyone can interact with them and they are free to use the site.
Take a look at the MEMBERS page and see for instance: user juanma.... or devils... they were not even supposed to show up there

ok check your admin settings, user settings, and make sure that mandatory user approve is checked, also check the other settings there, then go to users section and user roles and make sure those are ok. 

Then go to pages and check each page at the top (the button) and edit it and make sure they are the way you want them.