Unfortunately, early in Path Finder 8 development (around 8.1) we've introduced an error that ignored the option to skip upgrades check, and we've received the reports on this only after Path Finder 9 release. It's been fixed in the most recent version.
For Path Finder 8, please follow this workaround:
1. Quit Path Finder 8
2. Type in the following command in terminal: defaults write com.cocoatech.PathFinder SUEnableAutomaticChecks NO
Please feel free to write us back and we will be happy to assist you.