Try to delete the Finder's preferences (/YourHardDrive/Users/YourUserName/Library/Preferences/com.apple.finder.plist) and Dock's preferences' (/YourHardDrive/Users/YourUserName/Library/Preferences/com.apple.dock.plist & com.apple.dock.db). Then reboot. Plus try to make a Test User account and see if that account has problems.