1. Download the hotfix directly available on the Installshield website. This fixes the error that is displayed as 'Setup Is Unable To Find or Update ISScript.msi.' Navigate through the list of versions, download and install the hotfix by going to this URL:consumerdocs.installshield.com/selfservice/viewContent.do?externalId=Q108158sliceId=1
2. Set the permissions in the 'Installer' directory of Windows. If improper permissions are set, the Installer software is unable to copy files to a temp directory while processing. Navigate to 'C:\Windows\Installer' in Explorer. Right-click the 'Installer' directory and select 'Properties.' Click the 'Security' tab. Ensure that the 'SYSTEM' account and the administrator account have full rights permission on the folder.

3. Click the Windows 'Start' button and select 'Run.' Type 'regedit' into the box and click 'Ok.' Navigate to the registry key labeled 'HKEY_LOCAL_MACHINE\SOFTWARE\InstallShield.' Installshield requires full rights for the 'SYSTEM' and administrator accounts on this registry key. Right-click the key and select 'Permissions.' Add these two accounts and click the 'Ok' button.
4. Copy files from a network drive to the local hard drive. Some people try to use Installshield from a network drive. If the user does not have 'write' rights on the network drive, Installshield may fail.
5. Close all programs before running Installshield. Some applications may conflict with the installation. Ensure all applications are closed and try to run Installshield.