Can't sign in with Outlook plugin

Can't sign in with Outlook plugin

I've just installed the Outlook plugin for Outlook 2007. The Zoho toolbar appears correctly and I click the Sign in button. After entering the credentials, the message "Logged in succesfully" appears, but then nothing happens. I would expect the popup window to close by itself but nothing happens, and if I close the window manually, Outlook seems to be not logged in Zoho. In fact, the button Sign in is still active.

So it is impossible for me to log in. What can be the solution? This is an absolute necessity for us.