Error update_oC is not defined

[Silvio_Boezio]

Hi guys
Plesk Version: 12.0.18
Page: Control Panel > Tools & Settings > Mail Settings > Virus Protection Settings
Error: Clicking on OK button this error appears in the console and no changes are made (update_oC is not defined).
The hit count of this error increases every time I click the OK button.
There are other javascript errors too in the console:

SyntaxError: missing ) after argument list mail:428
ReferenceError: _body_onload is not defined mail:1
ReferenceError: _body_onresize is not defined

I cannot set anything in this panel.
I strongly need to set the antivirus option asap.

thank you!!