more things to try:
1) Get new Safari plist file: com.apple.Safari.plist
You'll find it in the Library folder that is in your Home folder, under Preferences (another folder)
Drag the file to your Desktop, then go into Safari
Safari will create a fresh plist file
No joy? No harm done.
More headaches? Put that file back, overwriting the new one.
2) Log in under a different User Account
If that solves it, Trash your other Account