[wix-users] Upgrade Installation

[R]

Is there a common newbie error that causes an upgrade to uninstall the
original program?

I have two products: drivers and the main app. Here are steps that create
the problem:

   1. Install 1.2.0.3.
   2. Change Bundle version alone and everything else is the same.
   3. Install 1.2.0.4.

Step #3 uninstalls the main app but leaves the drivers alone and all my
main app shortcuts (separate components from main app). The only difference
I can tell is that the main app components that disappear are those
generated by heat into a structure like the following:

<?xml version="1.0" encoding="utf-8"?>
<Wix xmlns="http://schemas.microsoft.com/wix/2006/wi">
    <Fragment>
        <DirectoryRef Id="INSTALLFOLDER">
            <Directory Id="dir242DC17B8DFC53C13CAF172FC08B730A" Name="de" />
            <Directory Id="dir43FCCFA109FBF584D9155DCE31E452EB" Name="x64"
/>
            <Directory Id="dir97F42FF68945B97AAE670945C4FDAE93" Name="x86"
/>
        </DirectoryRef>
    </Fragment>
    <Fragment>
        <ComponentGroup Id="MainApp_Components">
            <Component Id="cmpBB1767D7C200C536ABB2D361F40F9D92"
Directory="INSTALLFOLDER" Guid="{18EA1D5A-3C1A-4709-905F-19285C646D5A}">
                <File Id="fil4E0F4321F336BF83461A34116F3E30B7"
KeyPath="yes"
Source="$(var.MainApplication.TargetDir)\Microsoft.WindowsAPICodePack.dll"
/>
            </Component>

......

        </ComponentGroup>
    </Fragment>
</Wix>

"Repair" works and everything gets installed.

As a side problem, sometimes the drivers will reinstall even though they
are still there. Here is an example of what I have:

            <Directory Id="dir_serialusb" Name="Driver_SerialUSB">
            <Component Id="component_usbserialINF"
Guid="111c9893-c0da-4c17-8d1d-b2a2854ee1c4" Win64="yes">
              <difx:Driver /> <!-- Element to install the inf driver.-->
              <File Id="file_usbserialINF"
Source="..\BLED112-Signed-Win-Drv\windrv\usbserial.inf" Vital="yes"
KeyPath="yes"/>
              <File Id="file_usbserialCAT"
Source="..\BLED112-Signed-Win-Drv\windrv\usbserial.cat" Vital="yes"/>
              <RemoveFolder Id="rmDir_serialusb" Directory="dir_serialusb"
On="both"/>
              <RemoveFolder Id="rmDir_serialusb_drivers"
Directory="dir_drivers" On="both"/>
              <RemoveFile Id="rmFile_usbserialAllFiles" Name="*" On="both"/>
            </Component>
            </Directory>

Thank you for your help!