Running applications or their install program causes other application install to fire

[Muse]

I installed an audio utility a few days ago that I use occasionally, a
freebie named MP3 Gain. I downloaded the most recent version and
installed it, evidently without problems. I run the shortcut and
instead of the utility opening I get screens indicating that an
installation of Visual FoxPro 9.0 is in progress and I'm asked to insert
a CD in my optical drive!

I do have Visual FoxPro 9.0 SP2 installed, however the application wasn't running.

I uninstalled MP3 Gain and installed it again in a new location, and at
the end of the installation I left the checkbox checked to launch the
newly installed program. What started was the same screens asking me to
insert a CD in my optical drive and proceed with the installation of
Visual FoxPro 9.0:

Hitting Cancel causes the same screen to appear saying the feature
cannot be installed without the Visual FoxPro CD. The only way I can
terminate this is in Task Manager. Of course, I cannot run MP3 Gain.

The shortcut for the utility has this target:

G:\Apps\UtilXP\Sound\MP3Gain_1.2.5\MP3GainGUI.exe

I uninstalled the utility again and this time installed the old version
from 2002. I get the same bewildering outcome.

I'm looking at a little screen that looks like this:

--------------------------------------------------------------------------
Visual FoxPro 9.0 Professional - English
--------------------------------------------------------------------------

! Error 1706. No valid source could be found for product Visual FoxPro
9.0 Professional - English. The Windows installer cannot continue.

OK

--------------------------------------------------------------------------

I click OK and that screen disappears and I get another screen that
looks like this:

--------------------------------------------------------------------------
Visual FoxPro 9.0 Professional - English
--------------------------------------------------------------------------

The feature you are trying to use is on a CD-ROM or other removable disk
that is not available.
OK
Cancel

Insert the 'Visual FoxPro 9.0 Professional - English' disk and click OK.

Use source:

[ <edit box> ] [Browse... ] <-- button
--------------------------------------------------------------------------
If I click Cancel, it has a transitory screen saying "Preparing to
install..." and then I get the first screen again.

If I click OK, I get an hourglass for 12-15 seconds and then this:

--------------------------------------------------------------------------
Visual FoxPro 9.0 Professional - English
--------------------------------------------------------------------------
The path " cannot be found. Verify that you have access to this location
and try again, or try to find the installation package 'VS_SETUP.MSI' in
a folder from which you can install the product Visual FoxPro 9.0
Professional - English.

OK
--------------------------------------------------------------------------

I installed Registry Mechanic and when I tried to run it, I get the same crazy stuff happening. If I wait long enough, Registry Mechanic finally loads, though. I run it and it finds hundreds of "errors" and offers to fix them if I buy the program, $40. I looked for a freebie registry repair program and downloaded ccleaner and installed it and ran it, managing to get beyond the snafus and it found hundreds of problems and evidently fixed them, but this stuff keeps happening anyway. I'm told that an uninstall of Visual FoxPro isn't likely to resolve this problem and I may have to reinstall my XP Pro! Argh! Is there something else I can try?