Is your existing database named "member contacts.fp7"? Is that the name of a database file that contains data that is related to your current file?
This error typically appears when filemaker attempts to open a file that is needed because of a relationship, Perform Script or Import Records.
Have you perhaps changed the name and/or location of Member Contacts.fp7?
Yes! I was cleaning up the files on this computer, and moved "Member Contacts.fp7" to another folder in my documents. I just found it, moved it back to File Maker Pro, and my database opens! Thank you so much for responding to my message. You are amazing.