Can't log in to Nexon website

Posting for a friend:

He can't log in to the Nexon website on a certain account (his main, naturally). It tells him account doesn't exist or password is wrong.

He can log into the game (through GameLauncher) using that same account.
He can log on the site with other accounts.
He has tried different browsers, all give the same result.

Any idea what could be causing this and how to fix it?

He was hacked.

Doesn't seem that way.
His password wasn't changed (still works when logging in from GameLauncher), all his chars have all their gear, meso, etc...