Installing Net Expresss and getting an error stating AS is already installed.

Problem:

Installing Net Expresss and getting an error stating Application Server is already installed.

Resolution:

This sounds like an intermittent issue with the Net Express 4.0 installation.  

The following steps should be followed:

1) Using REGEDIT, rename:

   HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall

   to

   HKEY_LOCAL_MACHINE\\Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall-temp

2) Start the Net Express setup.

3) At the setup welcome screen, rename the above key back to Uninstall.

4) Continue with the installation.