I went over the word/letter cap link with all needed information.
Try, Open SteamGo to Steam in top left corner,Go to Settings,Under Account look for Beta ParticipationChange that to NONE,Let steam update
Not too sure this will help.
Please use this format to post your error.Did you read the F.A.Q?
I've been having the same problem, only it stopped doing it for like 2 times and let me play, then it started again and I haven't been able to fix it since