Anyone have this vista problem?

Ok, I'm having major issues with the administrative privileges on vista at the moment. To start off, it's not the simple Run as Admin "issue". The problem is that there is only one user account which is the owner/admin (I quadruple checked), but has no admin privileges. I've tried Trend virus scan, which I don't fully trust. I downloaded a copy of Mcafee (since I had 1 subscription left of the 3 it comes with) but didn't have admin rights to install it. I can't click/run anything with the 4 colored shield icon (admin icon) next to it, so no creating new accounts on the computer, changing admin privileges, admin cmd, etc. Any help? I'm betting that it's a virus...