Hi
I have run into this from time to time as well.
What you will need to do is log in as Administrator.
I don't know why this is required for some software but it is.
To log in as Administrator you have to go through this process...
Enable the Administrator Account
1. Open the command prompt with elevated privileges by clicking the Start orb, All Programs, Accessories, right-click Command Prompt and then select Run as administrator.
You will see a window with a place to type.
2. Type net user administrator /active:yes and then press Enter.
You can just cut and paste this in from this message.
Log off and you will see that you now have two options to log in.
Click on the Administrator one.
Install your software.
When you are done repeat the process and this time type or paste in...
net user administrator /active:no
Mike