Random thought. Does this occur only if you have "too many" games installed and listed in Galaxy? Somewhere around the time I had over 40 games installed it stopped working, but before that it seemed to work fine. I guess I'll test by uninstalling a few games and see if it resumes operation.
Edit: Nope, that's not it. But I noticed GalaxyCommunication service is not starting up. And I recall there being crashes related to it months ago, roughly back when it last worked in fact. Not sure why it now refuses to start.
Edit 2: Reading the GalaxyClient.log, I noticed that Galaxy is
somehow detecting each game being closed few seconds after they've been launched even though this is not true.
Edit 3: For those interested in this problem, look over to:
http://mantis.gog.com/view.php?id=4234