CAPTCHA is a security feature that helps protect websites from spam and abuse. A simple test to tell human and bots apart. It is easy for humans to solve, but hard for “bots” and other malicious software to figure out:
Simply click the box to the left of 'I am not a robot,' wait a few seconds for the spinning wheel to turn into a tick then proceed to click LOGIN.
If you see the 'Invalid captcha' warning on your screen (see above) you have either failed to click the box, proceeded to quickly to logging in after clicking it or selected a wrong image from the grid presented. Simple X out of the warning and follow the process again.