A few people are reporting that they are having an issue with the AVG software blocking the BYOND software from installing and running. This following guide should fix this issue.
I advise people to post on the AVG forum about the problem so AVG Technologies can fix it.
You may need a user account with administrator for this guide to work.

Step 1:
Download the BYOND installer ready to install from http://www.byond.com/download/

Step 2:
Click here to view the screenshot
Once you have downloaded the BYOND installer, open up the AVG User Interface. This can be often done by right clicking the AVG icon in the task bar and click left clicking Open AVG User Interface.

Step 3:
Due to the way that AVG works. We need to disable the Resident Shield for a short while so we can install the BYOND software.

Click here to view the screenshot
Once the AVG interface is loaded, left click (or double left click) Resident Shield.

Click here to view the screenshot
Remove the tick in the Resident Shield Active and click save changes.

Step 4:
Find where you downloaded the BYOND installer to and install it.
Don’t forget to click Allow on the User Account Control message if you get one.

Step 5:
Before enabling the Resident Shield again we need to add the BYOND software to the exceptions.
Open the AVG interface back up and go into the Resident Shield.
Click on the Manage exceptions button.

Click here to view the screenshot
Click on Add Path

Click here to view the screenshot
Highlight the folder named BYOND. Often this would be in C:/Program Files

Click here to view the screenshot
Once you done that click apply and then OK

Step 6:
Click here to view the screenshot
Re enable the resident shield ticking the Resident Shield Active box and click Save Changes

Congratulations the BYOND software should work with no problems and the AVG program should keep you protected.

This guide is not a discussion about other anti-virus software or why AVG is bad/good. Make a forum topic about it or a blog post elsewhere.