Piecing together fixes found at other forums, I was able to resolve my problem. I had been attempting to install an app from the Google Play and watched as the "Installing" screen never changed unless I ended the process. My next attempt was to remove the Play app and try to re-install from an APK. That too, failed. Constant reboots failed to resolve the issue as I'd eventually get the "Package Helper" failure alert.
I saw that others were able to fix the alert by removing or unmounting there SD card. I pulled the SD card and turned the phone back on. This prompted the completion of an Amazon app install that had apparently failed. Once the Amazon downloaded app installation completed, I was able to re-install Google Play. I then tried installing the original app from the Play store and that worked. Unfortunately, once I put the SD card back in and rebooted my phone, I started getting the Package Helper alert again. I am still able to install applications from Google but I was stuck with another failed Amazon app install until I pulled the SD card and rebooted again.
To be thorough, I put in another SD card. Same issues. Package Helper error and Amazon app store installation failure. Pulling the card and rebooting allowed the Amazon app to install. There is nothing wrong with either SD card as I can read and write to both. One was newly formatted. I forgot to mention that I am also unable to move apps to the SD card. This was not a problem in the past.