Cannot enter email address in login screen

The text box where I enter my email addy in the login contains a string of letters and numbers and cannot be edited or deleted. The password text box works fine.

Earlier I closed the client but didn't actually logout, and so I don't know why it is asking me to log back in. I've never seen this problem before. 

Tried reloading the launcher using the .msi, but it updated to the latest launcher version which, again, doesn't work.

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