You could go to Control Panel\All Control Panel Items\User Accounts and change your user account control settings. That's not a problem if you are the sole user, otherwise I wouldn't recommend it - the setting has nothing to do with your AV / Malware security, as is.
Another way could be, to add Take Ownwership Link Removed --- it has helped many. Nice, non resource using program, it can be helpful with other administrative issues too, Windows 7 is quite paranoid.