CAPTCHA not loading in Google Chrome, Firefox and IE

Hi experts!
Good day! May I know if somebody had already encountered this problem while using Google Chrome, Mozilla Firefox or Internet Explorer?
Whenever I'm about to fill-up or sign-in a registration form, the CAPTCHA code doesn't load. It only shows a box with an 'X' mark. I tried it in all of my internet browsers (Google Chrome, Mozilla Firefox and Internet Explorer) but all of them failed. Sometimes, I even got a blank space on the CAPTCHA box.

I also tried to refresh the webpage, disable my antivirus software and Windows firewall but still no good.
Any suggestion?
Thanks,
Richard
