Issue with Users Logging into Box.com and not Seeing Files Created in Another Box Account

We are having issues with users logging into new instances of Sparrow.Box.com with files/folders, and it defaulting them back to a previous version or another instance of Box.com.  We have created files/folders and invited our users to Sparrow.Box.com to collaborate.  When they click the invitation link to setup their account it is either automatically kicking them over to a pre-existing Box account and forcing the login from there, or they are able to login but are not able to see the files/folders they were invited to.  In some cases, they are being defaulted back to another instance when they login to Sparrow.Box.com, but when they click on the file/folder it defaults them to another Box site and they can't see the files/folders any longer.