TryFirst, Force quit Finder. You can do this by pressing the option+command+esc keys and then selecting Finder from the list and clicking on the Relaunch button.
Then, try deleting the Finder's preferences file: com.apple.finder.plist, found in ~/Library/Preferences.
rm ~/Library/Preferences/com.apple.finder.plist
This file seems to easily become corrupt. Trashing it is a good first step when Views become wacky—anything to do with Finder.