I had a similar issue and hopefully it doesnt match your scenario.

I began installing an applicaiton on a windows 98 fe machine. THe install shield wizard popped up a message that additional files need to be installed and the machine would have to be restarted before the app installation actually begun.

Like a dummy, I decided I didnt want to go through with the install so I tried to cancel. From then on every time I tried to install another app on that particular machine I got that error, another version is already installed.

I tried re-running again & again, no luck. I had to restore the registry on that pc to fix the issue. It had nothing at all to do which app had been installed on the pc. In fact, there were no apps installed on that pc at all.

In my experience, installshield "THINKS" there is another app there. That's not always true. THere may be some remnant in the registry, that is not getting removed.

I had the same issue occur again, but it was always on a machine with an older operating system. 98 first edition or earlier. A system that required additional files before the installshield could run.