It is possible that some AVCHD videos shown in the Importer will have the same thumbnail images that were already used for other imported AVCHD videos. The actual content of the imported video should be correct, only the representative thumbnail is incorrect. To resolve the issue browse to the following location:
"C:\Documents and Settings\"Account name"\Local Settings\Application Data\Pinnacle\Importer\NGThumbnails\
Windows Vista/ Windows 7 / Windows 8
Once in the NGThumbnails folder, delete the .thb2 files, and the correct thumbnail should appear.