Well, what do you know... my old friend Mr login problem just came back to pay a visit!

Yep. Same here. Using Firefox 28.

The problem is back for me too. No idea why, maybe because of the new Firefox version?

Nope I'm running IE and I had it too, the last two days. I actually thought I entered my password incorrectly, then I thought it was because I hit "Enter" instead of mouse clicked and by the third time I realized it must be on GoG's end... then I saw this thread :) Figured I'd toss in my 2cents and give the Firefox users some comfort that it isn't a browser issue

Same problem here. Yesterday and today (and maybe prior but I didn't yet notice it until yesterday).

Today I've logged in 3 times (across the whole day) and each time I had to log in twice.

Using Google Chrome. Have cleared cach and cookies but I don't think that's "it" because I browse in Incognito mode and that means the cache and cookies are cleared on browser exit (which I do between visiting different sites).

Ha! So it's the server gnomes in GOG fooling around again. =)

Seriously:
I've had this login nuisance about a week now. I use Linux Mint with Firefox, with HTTPS turned on when possible, on my current main computer. Seems to me though it hasn't got anything to with my settings on this machine since I've tried and faced the same problem also on different Vista, Win7 and Win8 computers.

I can just imagine all the gray hairs GOGs techies get while trying to solve this, as it seems to me that the cause might be some small change somewhere sometime last couple of months.

Anyway lets hope things go to normal soon. =)

Same thing here. Just started happening a couple of days ago. IE on Windows 8.1 and Chrome on Android.

Yepp, same problem here...nice to see, I'm not alone with this. ;o)

I'm having the same issue using Chrome. Perhaps the NSA is posing as GOG.

I've just had to begin logging in twice today with my new laptop, two days ago it wasn't an issue. I'm using Windows 8.1 and Firefox.

I also had to login twice, starting yesterday and today.

The luck of the irish promo had a similar bug for me:
I would be logged in, adding a golden pot often triggered a re-login popup which I cancelled, and just clicking the golden pot a agin seem to resolve that issue).

Perhaps they are related somehow, who knows. (the promo did end recenlty or around the time of this bug)

edit: I'm on firefox 27

Same problem here.

Keep in mind that the secure connection on the front page is broken for months now (ever since the Winter Sale) - even though you start at secure.gog.com the moment you hit the "Log me in" button, the site reloads and reverts to (plain) gog.com.
In case you have HTTPS Everywhere with the GOG rules installed you won't be able to ever log in to the front page, unless you disable the rules.
The sad part is that GOG Support has stated that it's a very low priority issue that they won't look into it before they're done with other higher priority matters.

FWIW, I was able to log in to the forum at my first try today using the latest Pale Moon and HTTPS Everywhere with the GOG rules. But as I said, the store front page doesn't acknowledge that I'm logged in.
But using SWare Iron and plain http, I had to log in twice before the site acknowledged it both on the store front page and on the forum.

That's at least an indication that opening gog.com or gog.com//* and then trying to log in doesn't work properly.

Interesting, I always thought the problem is on my end, using NoScript and restrictive cookie management et cetera. Apparently, that's not necessarily the reason. So, yeah, I'm in the same boat, having to login at least twice.

No problem this end. Used Opera 12.16 from my Windows 7 computer & Opera 12.15 on both my android 2.x and 4.x devices....