I got this from the AVG website:
If you are installing AVG 8.0 Free Edition and the installation process fails, there are several steps you can take to install AVG Free successfully.
1. Make sure you are installing AVG under an account with Administrative rights
This step is vital for correct and successful installation, since AVG needs to copy some of its files into folders, which are not accessible by an account with User permissions.
2. Always use the latest AVG installation file
AVG program is being improved continuously, including the installer which is responsible for correct installation process. Moreover, using the latest installation package eliminates the need to download larger program and virus base updates immediately after installation. To download the up-to-date installation file, please visit the Download section of our website.
3. Close all running programs, disable security applications
Before running the installation file, please close all unnecessary running programs and make sure that there is no security application on your computer which might interfere with the installation process. Typical examples of programs preventing successful AVG installation are anti-spyware utilities and registry monitors/cleaners, which are preventing access to Windows registry. AVG needs to be installed also into registry to allow the functionality and protection it was designed to offer.
4. Remove possible conflicting applications
If you are using an application which might be in conflict with AVG, please disable it or uninstall it completely before running the installation. In general, AVG may conflict with such application, that provides similar or same functionality as one of the AVG components. This is especially important for other programs with one or more of these features:
- real-time protection against viruses (same as AVG Resident Shield)
- checking or filtering of e-mails (same or similar to AVG E-mail Scanner)
5. Disable UAC (Windows Vista only)
On Windows Vista, the function User Account Control may in some cases create a copy of specific AVG files in a virtual folder. This limits AVG functionallity after the installation. The UAC function can be disabled in Windows Control Panel -> User accounts -> Turn User Account Control on or off -> uncheck "Use User Account Control (UAC) to help protect your computer" -> click OK button and restart the computer.
This post has been edited by Lloyd T: 16 November 2008 - 04:49 PM