Connection string - where should it be stored and why?

Hi,
I'm looking for alternatives on where to store an encrypted connection string to a database.
I can't store the connection string within a XML config for the variety of reasons, mainly to do with business requirements.
I have considered storing it in the isolated storage (user/app level) or the windows registry.
I'm interested to find out what problems I might encounter if I got ahead with registry or isolated storage options. Is there any alternatives?
 
Thank you
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