Too many Ads in Safari

Go to Safari menu (At the very top right side of your screen next to Apple icon), choose "Quit Safari"

press "Shift" button and while holding this button on your keyboard single click on the Safari icon on your Dock.

Open Safari - Preferences - Privacy - Remove All Website Data.

Go menu with Option (Alt) key pressed - Library - locate Safari folder and move it to your desktop.

To get rid of ads, I'd recommend using Adwaremedic. It is a tiny tool, which will remove the adware within several seconds. You can download Adwaremedic from this website: http://www.adwaremedic.com/index.php

You can also remove the adware manually using the steps provided by Apple: https://support.apple.com/en-us/HT203987

Also, I believe it would be a good idea to install AdBlock.

Hope this helps!

You are welcome.

1. That's a good choice, it helps in most cases.

2. Your reading list should remain intact. At least mine always remains after I delete website data.

3. In this case, I recommend to restart your computer and check whether everything works fine. If you still face the same problem, you should try the manual removal of ad plugins.

Minimize all the windows, press and hold the Option hey and while holding it click on the Go menu. After that, select Library and locate the Safari folder. Once you find it, drag and drop it to your desktop.

Try a restart.

Do a backup, using either Time Machine or a cloning program, to ensure files/data can be recovered. Two backups are better than one.

Try setting up another admin user account to see if the same problem continues. If Back-to-My Mac is selected in System Preferences, the Guest account will not work. The intent is to see if it is specific to one account or a system wide problem. This account can be deleted later.

Isolating an issue by using another user account

If the problem is still there, try booting into the Safe Mode using your normal account. Disconnect all peripherals except those needed for the test. Shut down the computer and then power it back up after waiting 10 seconds. Immediately after hearing the startup chime, hold down the shift key and continue to hold it until the gray Apple icon and a progress bar appear. The boot up is significantly slower than normal. This will reset some caches, forces a directory check, and disables all startup and login items, among other things. When you reboot normally, the initial reboot may be slower than normal. If the system operates normally, there may be 3rd party applications which are causing a problem. Try deleting/disabling the third party applications after a restart by using the application un-installer. For each disable/delete, you will need to restart if you don't do them all at once.

Safe Mode

Safe Mode - Mavericks also Yosemite

I suspect that this is due to a hacked network device. See:

http://www.adwaremedic.com/kb/hackedrouter.php

(Fair disclosure: I may receive compensation from links to my sites, TheSafeMac.com and AdwareMedic.com.)