Opera 9.20 release SpeedDial feature that cached tumbnails of your favorite websites.
CCleaner to improve cleaning capabilities can detect tumbnails and clean then if didn`t affect SpeedDial configurations, who must be preserved..
Folders of Opera:
\Application Data\Opera\Opera\profile\thumbnails
\Application Data\Opera\Opera\profile\cache4
\Application Data\Opera\Opera\profile\images //Current version of CCleaner didn`t delete the favicons