If Safari is behaving strangely, one or more of the suggestions we've collected may prove helpful. If not, there's always Apple Care!
- Run Safari in safe mode and see if the issue continues to happen. If it doesn't, something that's being loaded on startup is the most likely cause. Apple Support has some Safari troubleshooting tips to try.
- Troubleshoot Safari freezes and crashing in OS X Yosemite.
- If Safari is misbehaving after a MacOS upgrade, try these troubleshooting steps from AppleToolbox.com.