Take a look http://support.installshield.com/kb/view.asp?pcode=ALL&articleid=Q106405.

>Hi all
>
>I just installed the sp4 for installshield express (the real verson) and now I can't build my install. I get the following error.
>

>Merging Microsoft Visual FoxPro 7 Runtime Libraries: C:\Program Files\InstallShield\Express\Modules\i386\Vfp7Runtime.msm
>  ** Fatal Error: Error merging Microsoft Visual FoxPro 7 Runtime Libraries with module ID
>
>C:\Program Files\InstallShield\Express\Modules\i386\Vfp7Runtime.msm
>

>
>Any idea how to fix this?
>
>Thanks