First of all, ensure you are using Ad-Aware version 8.1 or higher.

You can check this by clicking the "About button" at the bottom right of the Ad-Aware mainscreen.

Ensure you have an active internet connection

Configure your firewall or any other security programs to allow Ad-Aware (aawservice.exe) network access. If necessary, you can temporarily turn off your firewall, but be sure to turn it on again after you have updated the Definitions File.

1. Open Ad-Aware main menu.
2. Click the 'Web Update' button to connect to the update server and download the latest software and definitions updates.
(if you're experiencing 'connection error' when clicking web-update, click here.)

3. When the update is complete, click 'Ok'.

If you are operating behind a proxy server, you will need to have your proxy server settings correctly configured in order to perform updates.

Go to Settings -> Updates and click proxy settings.

Tick the box beside "Enable Proxy", enter your proxy server address (in the format,  proxyname:portnumber ) your username and password and click 'Ok'.

You can also manually download and update the definitions file.

1. Download from http://download.lavasoft.com/public/core.zip

2. Extract the file (core.aawdef) directly to the Ad-Aware folder, either:

XP:

* C:\Documents and Settings\All Users\Application Data\Lavasoft\Ad-Aware\Defs

Vista:

* C:\Program Data\Lavasoft\Ad-Aware\Defs

(note: You can also go to, update->settings and click 'import' browse to where you have saved (core.aawdef), select this file then click 'open' and 'ok'.)

3. Close and restart Ad-Aware from the System Tray icon.