I think what happened here is that something went wrong and messed up the permissions of some of the users files. MS help suggested that he login as an administrator and reatore the intended permissions.

I don't work with Windows boxes, but see a similar situation come up often enough on Linux boxes. Typically, the cause is that the user elevated to root (e.g. the administrator account) and did something that probably should have been done from their normal account. Now, root owns some user files and things are a big mess until you go back to root and restore the permissions.

It use to be that this type of thing was not an issue on single user machines, because the one user had full privileges. The industry has since settled on a model of a single user nachine where the user typically has limited privileges, but can elevate when needed. This protects against a lot of ways a user can accidentally destroy their system.

Having said that, my understanding of Windows is that in a typical single user setup, you can elevate a single program to admin privileges by right clicking and selecting "run as administrator", so the advice to login as an administrator may not have been nessasary.