Safari?

If you have not done so yet, just try restarting your computer. If that doesn't help, try Safe Boot mode.

Try Safe Boot mode by holding down the Shift key at startup. Safe Boot is quite slow because the OS performs some cleanup and verification tasks, so give it time. After you're completely logged in, restart normally.

If the above doesn't work, you can try this.

Safari Corruption See post by Linc Davis