Why does my finder window not allow for re-sizing?
In Finder, type Cmd-G.
Go to ~/Library/Preferences.
Move com.apple.finder.plist to Trash.
Log out and back in.


That should resolve the issue. If not put the plist file back in it's original place (deleting the new one the system generated.

If that still doesn't work, create a test user account. Login to that and test it there. If the issue persists in this test account, you will need to reinstall the operating system most likely.