See if Re: Problem with Install Shield Express for FoxPro 9 Message #1158020 answers your question.

>I have an interesting problem when upgrading my VFP5 application to VFP9.
>My VFP5 application was build some years ago and works fine. With InstallShield Express 5.0 for Visual FoxPro I build an Upgrade for this task, where I replace some directories with the same name, exe with the same name, but another version. The problem is, that some of the files doesn’t replaced (It may be also PDF or Borland DLL and vfp exe). So I must remove these files before Upgrade, but it is not comfortable, because we have thousands of customers with VFP5 application. With application of VFP8 it does not happens.
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