Outlook - permission to modify folder

[Clumps19]

In office 2010 using W7 professional (all updates installed), when editing contacts I sometimes get this message:

"Your changes cannot be saved because you do not have permission to modify some or all of the items in this folder. Do you want to save a copy in the default folder for this item?"

I have full administrator rights - can anyone explain why this comes up and how I can stop it?

Thanks

[Clumps19]

In my question concerning editing contacts, I have noticed that when bringing up a contact in Outlook, each one is marked "read only". Does anyone know why this should be and how I can change it?

Thanks again