You do not mention your operating system, but I assume that you are on Windows.
Try uninstalling your current Reader from Control Panel | Add/Remove Programs. If that also gives you an error, remove it using the Windows Installer Cleanup Utility.
Once removed, download the installer http://ardownload.adobe.com/pub/adobe/reader/win/9.x/9.3/enu/AdbeRdr930_en_US.exe (English version); save it to disk, then close all browser windows and run the downloaded installer.
If this does not work, please specify your Windows version and the full 1500 error message.
I am answering to your original post so that you may edit your last one if you wish so. Are you sure that you want all that information in your signature made public?