Hi,
Thank you for posting the query on Microsoft Community and we are happy to help you on this issue.
Please provide us with the following information related to this issue:
1. How are you trying to install Sage 50 2013? Are you using any media or did you download it online?
2. Is the issue confined to Sage 50 2013?
I would suggest you to boot the computer into clean boot state and try to install Sage 50 2013.
Clean boot- It’s a process wherein you can start Windows 7 by using a minimal set of drivers and startup programs. A clean boot helps eliminate software conflicts.
Follow the link below to perform clean boot:
“How to perform a clean boot to troubleshoot a problem in Windows Vista, Windows 7, or Windows 8”
**http://support.microsoft.com/kb/929135**
Note: Please go through the section: How to reset the computer to start as usual after troubleshooting with clean boot of the Kb article to boot the computer in normal startup after fixing the issue.
If you have already downloaded Sage 50 2013 and trying to install, I would suggest you to delete the file that you have download and re-download the file and try to install it.
Let us know the status of the issue after performing the troubleshooting steps. If you need any further assistance or information about Windows, I will be glad to help you. We, at Microsoft strive towards excellence.