First, we discovered that the Color Finesse 3.0.7 installer on our website was corrupted and would install a bad version of the LE plug-in. The PI plug-in would install and work correctly, but LE would fail as you describe.
We've uploaded a corrected version of the installer to the website. You can re-download that and run it to install a valid version of Color Finesse LE 3.0.7. There is no need to uninstall Color Finesse first.
On the serial number issue, it's a bit complicated, so bear with me while I explain. Starting with CS 5.5, Adobe elected to stop including a Color Finesse serial number sticker or serial number in the download emails. Instead, Color Finesse is automatically serialized when the Adobe installer runs.
You can see that serial number in the Color Finesse "About" dialog after CS 5.5 has been installed. Best practice is to view that About dialog and write down the CF serial number for your records. Which no one does, of course.
With the CF 3.0.7 installer, we've made it so that if Color Finesse 3 has been previously serialized, we retrieve that serial number and fill those fields in for you. When it works, it's very convenient.
There are cases, however, such as failed installs, where the record of the earlier serial number is lost. In those cases the installer will still require that you manually enter the serial number. If that happens to you, the only way to get the Color Finesse serial number back is to uninstall and reinstall After Effects. Fortunately, with CS 5.5 that's a much quicker process than it used to be and takes very little time.
Hopefully running the latest Color Finesse installer is all you'll need to do. But worst case is just that uninstall/reinstall of AE and you'll be back up and running.
Bob Currier
Synthetic Aperture