Akonadi and Gmail

Hello to everyone,
since about a month (or maybe a bit more), I'm having troubles with the Gmail 
authentication setting in KMail. Whenever I start my PC, a browser window 
opens with the login page from Google accounts and asking whether I want to 
authorize Akonadi Resources to access Google services. Every time I accept and 
are redirected to a page saying "You can close this tab and return to the 
application now".

This also happens if I start up my PC from hibernation and also sometimes 
(seemingly randomly) when the system has been running for hours.

I'd expect that, after allowing Akonadi to access Google Service once, I 
wouldn't have to do so again (and, indeed, this only started happening 
recently).

Even more annoying is the fact that if I close the browser after the "You can 
close this tab..." message, I remain logged in my Google account, which I most 
definitely don't want.

Has anyone else experienced something like this?

Thanks in advance

Stefano