Funny enough, a few days ago, I ran into the same problem (FF), all what I had to do was actually to log out once and log in again, since then no problem anymore. Had to do with me changing my password.

this wouldalso delete / invalidate your cookies so this is just a cookie (and possibly cache) problem ;-)

Yep, and no need to delete all of them what a few guys have suggested ;)

Cache seems not to be involved, as I only logged out and in again. So something to do with one of the cookies, but was to lazy to check for it. Only funny didn´t had the problem prior, only after changing my password it did happen.

Had the same problem I guess I had too many programs that stored cookies (firefox, ccleaner, etc) so I once I deleted the ones in ccleaner (i think) it cleared it up.

CCleaner just removes trash like cookies and so on and does not store or create cookies ;-) It will delete the cookies of your browser if you set this option.
Did not check this but I regularly clean my PC from cookies and so on as they aremostlynot needed ;-) =)

Might be the case that there is a new cookie created when you change your password which forces you to relogin but this cookie is not invalidated / deleted properly.

It is a feature, not a bug ;-)

Could we at least get a word from someone at GOG on this? It's quite annoying.

Do you still have the problem? I never had this problem and others solved it by deleting the cookies.

I'm still getting the issue, and I didn't delete the cookies.

Did you try the following:

Log in, so that you see properly account on the top next to the shopping cart.
Log out via account -> logout, afterwards restart your browser and log in, close browser and it shall work (did at least for me ;) )

You should delete the cookies and cache, this should solve the problem and the next login works without any issues.

That seems to be working.

Good to hear ;)

For me this happened after password reset (on my wish ;) )