Vista - Admin Probs

Hello
I am having ALOT of problems with the admin
Alot of my games will not work I.e. Battlefield 2 they say I do not have
enough O/S privileges even if I run program as a admin
I am also having problems with other things as well like updating software
and games and also deleting some files from my documents as well as the start
menu it says I do not have permission (the admin thing again)

I have tried turning UAC on and off but this only seams to solve 1-2 issue’s
but just comes up with more problems and I have looked around but cannot find
a solution to this

I only have one profile on this computer as I am the only one that use’s it
so there is no need for passwords and/or hundreds of profiles

I install/update/uninstall/delete alot of things on the computer and/or the
External hard drive so this problem is becoming quite frustrating

Can you please help

Thank you