I don;t know if this is the only or definitive answer, but i checked my
tasks to see who was listed as the owner since I too am the only user on my
machine.It lists the name i have in my email account. I checked several
tasks spanning the last month and the "owner" changed to reflect the name
that i use in the account information page.
IN outlook/tools/email accounts/view or change existing/next/change/ YOUR
NAME.....
see what it says. and then change it...and see if that does the trick for
you...i know for me, the name that is in that field is what shows up as the
owner in my tasks.
f57