Hi there, @Raddish
I would like to say sorry for the inconvenience that you are experiencing. To address your issue, could you start off by re-downloading the latest client at the link I have below. Before downloading the new client again, please be sure to remove and delete all other PRO client files from your system.
Client Downloads
After you are done downloading again try logging into the game regularly. If you still are experiencing problems try the trouble shooting options down below:
In the case that none of these options help fix the issue, please let it me know here for further assistance.
Deepest Regards, Caliph