Vista accounts

I help our local church with their systems. One of the employees has a
laptop that had been originally assigned to someone else. She changed the
username from 'firstusername' to 'newusername' and has been using the
system. If I look at a file explorer I see a folder for 'newusername' that
contains all of her profile, etc. If I look under Users, I see the
'firstusername' with all of her stuff. I assume that the folder with her
username is just a pointer to the original user folder under Users and that
they share the same SID (if it is still called that).

Here is the problem: She installed Office Pro under her account (which is
really the original account--just renamed). She is listed as an
administrator and is the only account listed other than guest. When she
tries to run any office app it fails in some way or another unless she uses
"run as administrator" when she opens it. She has reinstalled several times.
Is it possible that when it opens the UAC dialog during the install it is
somehow getting confused and associating it incorrectly?

Thanks,

Tom Harbin