Make sure you're installing it to the correct folder. Premiere Pro is a bit "different" in where it expects to find plug-ins.
You need to choose the correct folder for your system's language, within the Plugins folder. For US English, that the "en_US" folder. So for CS3, the complete path would be "c:Program FilesAdobeAdobe Premiere Pro CS3Plug-insen_US". Or "Program Files (x86)" if you're on Vista 64.
If this is a fresh OS install of XP SP3 or Vista SP2, then you'll need to being using the current version of Color Finesse, 2.1.10. Microsoft has dropped some DLLs from the latest version which Color Finesse was (incorrectly) relying on being present.
Other reasons for failing to load would be not having QuickTime installed, or using the incorrect installer (something other than the "for AE and PrPro" installer).
Note that there have been a number of other fixes which affect Color Finesse with Premiere since 2.1.7. The current version is 2.1.10, which you can download from our website and install with your current serial number.
Bob Currier
Synthetic Aperture