This is really weird.
I have been a member of Spotify since 2009 and linked the account to my Facebook account in autumn 2011.
Now, if I log out, the email address that shows on the login screen is the address my Facebook account is registered to (my Spotify account is registered to a different email address).
I cannot log in using the Spotify registered address and the password which works to open my Spotify account on the web, even if I tell the player login screen not to remember my details, close it and reopen it.
My account on the web tells me, when I try to change my account email address to the same one I have for Facebook, that that address is already registered to another Spotify account. But it also tells me that I have already linked Facebook to Spotify.
But it does look like I only have one account: if I open "My account" when logged in through Facebook, it goes to the account with the different email address, and which is the one I pay subscription for. I'm on Unlimited when I open it through Facebook, and I know I only pay for one subscription.
Is there a way to get them on to the same email address and allow me to open the player without always having to log in to Facebook first?