JMich: It does? Why is that? If you are talking about the chat thread, using the old nick should still work. So it's a db problem, not a username one.
Having to remember the url for the old username and hand it out to those wanting to communicate privately with them defeats the purpose of changing said username, doesn't it?
Either way, using the old username is not an acceptable solution or reasonable workaround - sending a PM to a user and/or viewing their public wishlist, whether they've changed their username or not, should not require anything more than hovering over said user's avatar and selecting the corresponding option.
Since special characters are allowed in usernames, users that want to change their username are not obliged to know, or even take into consideration, that GOG may have a db problem that breaks some site features if the new username contains any.
Whether this is a problem with special characters on the db level, or GOG just neglected to update their db for some users (and I hope that this is not done manually), they should look into this problem and fix it.
JMO
