When you select "open remote" do you see the server listed? If you select the server, can you see the hosted file listed? Those details may help folks help you to figure this out.
Under Hosts I see the Host - by IP address - in the network path the I see fmnet:/ server IP address/ - putting Portal after the second slash and selecting Open gives the error message above.
I do this on the user's old machine and it works fine. I know the file exists because other users on other machines are getting to the file. I can ping the server from this new machine but something is not allowing the program to talk to the server.
I don't know if this is also an issue with FileMaker 9, but with FMP 10 and 11, sometimes this happens and you can fix it by copying the server.pem file from a computer where this works to the computer where it doesn't.
For More Information see: FMP installer does not install server.pem file
This is one of many acknowledged bugs that can be found in the Known Bug List here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: http://www.4shared.com/file/8orL8apk/FMP_Bugs.html
That fixed it. Thank you ever so much.
And now I'll update my bug database record to include FileMaker 9...