I have experienced both the problems reported here within the past 24 hours.
Firstly I tried to withdraw 500EUR to my Santander UK bank account but it failed.
I figured maybe Santander UK just doesnt do SEPA properly and handily I have another bank account in France which should certainly work.  Unfortunately I cant even add this second account to Kraken as it just keeps giving me a 'Bad Data' response whenever I try.

Im guessing this may all have something to do with the huge surge in popularity and use that Kraken have experienced in the last week, and it's understandable that bugs will appear in the system when it is this heavily used.  I have opened a ticket and am waiting to hear back, if I do I will let this thread know.  I will also post this to the main Kraken thread as a couple of you here are probably in newbie-jail.  One of their team seems to post over fairly often there so maybe he can help.

Other thread: https://bitcointalk.org/index.php?topic=290799.520