Problem with Help (i.e. ?Log, ?Plus, etc.)

I am running Mma Home Edition, on Mac OS X Version 10.10.5 (MacBook Air).

I restarted my system and now "?" does not work! Here is some sample output:

?Log (I entered this, and got the following errors)

Log
System`
CreateUUID["Info-"]
False
False
False

It had worked perfectly for years, until I had to restart the system (for reasons unrelated to Mma).

Any thoughts
Thank you.