Most likely the installer or the plug-in got corrupted in transit. Please download the latest Altiverb 7 updater installer on the computer you want to use it on. Then move the downloaded zip file on the desktop and there choose to extract it using the Mac OS X default Archive Utility app. Once you did this please run the updater installer from the desktop to install the correct Altiverb aaxplugin and this should cure the problem.
The aax plug-in can get corrupted when transferred on some external (or network) drives. The plug-in won't validate properly.