After reading dozens of blogs and possible solutions on this problem - I have now solved it, this is it:-
The problem is SAFARI's encrypted Keychain being corrupted in some way. This is about the 10th problem I have had with Keychain in Yosemite.
To solve this follow these steps.
1. Go to Safari Extns, write down your list of extensions you want to keep.
2. Quit Safari
3. Go CMD + U - To the Utilities Folder on OSX.
4. Run Keychain
5. Search SAFARI in the top right.
6. Delete all the keychains for Safari.
7. Quit Keychain.
8. Run Safari and Reinstall your extensions that have been removed.
SOLVED.