The complete message is similar to:
The feature you are trying to use is on a network resource that is unavailable. Press OK to try again. Enter an alternative path to a folder containing the installation package 'Isscript.msi' in the box below.
This error is caused by the ISScript program, which is installed on your computer.
To fix the problem, remove the ISScript program and its' registry entries:
1. Open Control Panel / Add or Remove Programs.
2. Select the ISScript program in the list and press Remove.
NOTE: It is possible that the ISScript program is NOT in the list.
NOTE: If you receive the above error while removing the program, exit Control Panel.
3. Start / Run / Regedit / OK.
4. Navigate to HKEY_CURRENT_USER\Software\Microsoft\Installer\Products\799411B8369C3D11BBDA000CF495697A.
5. Delete the 799411B8369C3D11BBDA000CF495697A sub-key.
6. Press Yes to confirm the deletion.
7. If the ISScript key or the 799411B8369C3D11BBDA000CF495697A key appears at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall, delete it and confirm the deletion.
8. Exit the Registry Editor.
9. Shutdown and restart Windows XP.