Hi dizzypc,
· What is the name of the software you’re trying to install?
· Is it compatible with Windows Vista?
Check the software compatibility
As of now, I would suggest you to follow the steps mentioned below.
Step 1: Run the software in administrator mode
How do I allow an application to run once with a full administrator access token in UAC?
Step 2: Re-download the software and install it by putting your computer into clean boot mode.
A clean boot helps in eliminating software conflicts. Visit the link below to know how to put the computer into a clean boot.
How to troubleshoot a problem by performing a clean boot in Windows Vista
http://support.microsoft.com/kb/929135
Note: Once you’re done with troubleshooting, reset the computer to start as usual.
Hope this information is helpful and let me know if you need any further assistance.
Mouneshwar R – Microsoft Support
Visit our Microsoft Answers Feedback Forum and let us know what you think
[If this post helps to resolve your issue, please click the "Mark as Answer" or "Helpful" button at the top of this message. By marking a post as Answered, or Helpful you help others find the answer faster.]