Run Software Update and see if a newer version of Safari shows up. If so, install it. If not, you might have to do a reinstall.
Or, another alternative, though not guaranteed to help, is to dump the com.apple.safari.plist file. The computer will make a new one, set to factory defaults. It certainly will not do any harm. This file is found in the Preferences folder within your Home / Library folder. but that Library folder might be hidden.
What is your OS version? Knowing that, someone can help you find that Library folder.