If didn't help.
- Press Start

- Write "local Security Policy"
- And give me screenshot of those to circled options.
- Look through 2 options cicled with red. can you see anything that can block installation

Note: second circled option "configure rule enforcement" is under Applocker
Note2: you may not have Applocker if you are not running Windows 7 Enterprise or Ultimate 
Quote: Originally Posted by
drlinberto
when i look at my user in user management I see i am an administrator.
but hey , I was just thinking of it, when i installed windows , I did not set up an administrator password, so how can i login as admin ?
If you have created only one account then you are administrator.
But UAC downgrades you to level of Standart account in some case for security reasons. and "run as admin" is function to bypass UAC