Problem on Re-installing Des2K?

I have tried to reinstall Form Generator 4.5.9.0.0 from Designer/2000 in Win95! During the installation process, I see that the installer copy all the required files into the designated directories. And then it "Modify the Environment Variable" (the message display on the installer's message box). At this time, a general protection fault appears that states that ORAINST.EXE is conflicted with ioexe.dll and the installion is destroyed.

In fact, I have installed the whole software before and there is no such problem appears!

Are there some location in win95 that stores the Environment Variable of the form generator? This problem only occurs in form generator. For other module such as Report Generator 2.5.????, it seems that there is no problem appears and the oracle installer update the window registry after modifing the Environment Variable of report 2.5. Then it quotes "successful".

Thanks!
ps: I found out that the installer install each component by seeing

    *.ins files in Win95's Designer/2000 version. That is,     cgenf45.ins is call when installing Form Generator 4.5.9.0.0.

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