I followed the steps to move the act files without restoring. I moved them into the Public Folder on the host computer. I went to the client computer and tried to open it and received the same error message as before. From the client computer I can open all the documents I have in the Public folder except for the act files.
Don't use an already existing Public folder. Instead, create a new folder directly on the hard drive of the server and fully share it out. You might also try creating a new database in that directory, sharing it and testing access, to see if the issue might be with the database itself.
Note: Effective 6/1/13, Sage no longers provides support for the Act! software. This is now provided by Swiftpage.