Error 1925. You do not have sufficient privileges error

Hello,
I am trying to install Opera 10 on my Windows Vista Ultimate machine. I keep getting an error message that I cannot install the software. It says that I do not have privileges.
Error 1925. You do not have sufficient privileges to complete this installation for all users of the machine. Log on as an administrator and then retry this installation.
I am logged in as an administrator and still I am not able to perform the installation successfully. I tried to research the web and found that I can use the, Run As command. I right clicked and selected Run As administrator but still I get the same error message.
Can anyone help me with this error message?
