The purpose of The Paper Tiger import/export function is to be able to move database between one Paper Tiger database to another.
The "Import" function is not designed to import Excel files or manually developed ".CSV" files that are external from Paper Tiger.
Since PT 3.0 is no longer being supported (see Support Calendar), we have not tested it to see whether it is compatible with Win7. Your best bet will be to get an upgrade to our latest version (4.1) and you should be able to import your old files without a problem! Please let us know if there is anything else we can do to help.
The Paper Tiger Team