i also use adium. Yes go to ....
system/coreservices/dock/contents/resources
Replace finder.png with the desired image you want. Enter admin password to verify if asked. Go to user/library/preferences and delete......
[link]
[link].plist
Open terminal found in /applications/utilities and type.....
Killall Dock to refresh dock and clear cache.
Always backup your files before you delete is good idea.