Anybody have any idea why the "fast user switching" option would be greyed out in my system preferences?
How many users do you have? the other account is enabled?
I have three users, and their accounts are all enabled.
Try checking the box for fast user switching. That made the menu name active for me.
I can't even check the box:
Try another admin account.
Try booting into the Safe Mode and see if the same problem exists:
Starting Up in the Safe Mode
What is Safe Mode
Retrieving data ...