[Brian]

Sorry for the confusion here - it looks like your sync settings got edited accidentally, which is causing omnifocus to look for the sync files in a location that doesn't exist.

You want to edit your sync settings so they read
https://idisk.me.com/<your mobile me user name goes here>/Documents/

Basically, there needs to be a double-forward-slash after the colon in the address, and unless your MobileMe user name is "mylocation", the middle section of the settings may not be correct. It should be whatever appears before the "@me.com" part of your MobileMe email address.

(If you're using the "Advanced" sync tab, another option would be to switch over to the "MobileMe" tab and let OmniFocus fill in the settings for you.)