The last time i used Ad-Aware on my test system (May 17th, 2008), i got this:

Looks like the new updates are no longer compatible with the old AA106

You can download the last update known to work here

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        The latest version, Ad-Aware 2007 Free, is not compatible with Windows 9x/ME. Ad-Aware SE 1.06 msi installer will work on your Windows 95 system, provided your Windows installer has been updated to Version 2.0. If , for any reason, the installer still doesn't work, use the following workaround. The Ad-Aware main executable program will run perfectly well in a Win 95 environment and is all you really need. Just download Ad-Aware.exe (v1.06r1) and unzip it to C:\Program  Files\Lavasoft\Ad-Aware SE Personal. It will be barebone, with no documentation and only the default english language. The first time you run it, you will receive an Error while loading definitions file, click [OK] to ignore. When the interface opens, the first thing to do will be to get the definitions file from the net, using the WebUpdate icon (second from the top right). After the update is complete, you are in business, ready to scan!

        Note:Older Ad-Aware's onboard updater no longer works. Download my updater or use manual update instructions below.

        Definition updates for Ad-Aware can also be performed manually by downloading the latest defs.zip and unzipping it in the same folder as the executable, then restarting Ad-Aware.

        Additionnal languages are available. The Language pack for Ad-Aware SE installs properly in Windows 95.