In windows vista home premium, by default the Administrator account is disable for security purpose.
But running windows on different users, you will end up with permission prompts when you try to open or install any application 😦 .
Simple solution just enable Administrator account. to do so please follow the steps :
step 1 : Run command prompt as Administrator
First you’ll need to open a command prompt in administrator mode by right-clicking and choosing “Run as administrator”.
step 2 : Now type the following command:
net user administrator /active:yes
You should see a message that the command completed successfully. Log out, and you’ll now see the Administrator account as a choice. (Note that the screenshots are from Vista, but this works on Windows 7)
You’ll note that there’s no password for this account, so if you want to leave it enabled you should change the password.