Been having the same issue, so has my husband. Happened to both of us on 3 different machines (his old and his new, plus my machine) right after a patch (and the forced move to Launcher 4). Launcher 4 has been an absolute headache for me.
Edit: I've taken to just bypassing the launcher altogether. As long as I skip the launcher, I never get this error and can login just fine. Since I never had this trouble using the small blue station launcher and I never have the trouble if I bypass the launcher it seems to me that L4 is what's causing me and my husband the problem.