Android Package File is Invalid

How to: "Android Package File is Invalid" message when attempting to install or update an app on the play store.  These steps worked temporarily on my device, but only worked for one or two installations.  

Later, even with no other changes, applications began to install properly.  It may be the PlayStore was having problems during this time and perhaps the best action would have been to wait a day or two.  I am unclear on this. 

Temporary Steps:

These steps temporarily allowed me to install applications.

1.  In Settings, Apps, select tabbed-item "Downloaded (apps)"
     Scroll down and locate "Google Play Store"; click to open

2.  In the list, about half-way down, click "Clear Cache".
3.  Click "Force Stop"

4.  From a PC or other workstation (or from your phone's browser), open
     "https://play.google.com/store"

5.  Scroll to bottom of screen; click "My Orders and Settings"
     Click the Settings Tab
     Give each "My Device" a Nickname by clicking the Edit link.
     Confirm "Show in Menus" is checked.
     Click "Update"  for each line-item changed.
     (These are probably good things to do anyway, for other reasons)

6.  From the phone, re-launch the App Store and attempt your update.

This resolved the problem on my phone.  If this fails, consider the following, which has reportedly also worked:

A.  In Settings, Apps, Select tabbed-item "Downloaded (apps)"
B.  Uninstall Updates and Clear Data and Cache.
C.  Re-install PlayStore Updates and try again

I noted in my testing on my phone, a hard-reboot of the phone fixed the problem one-time, but it re-occurred.


Not Recommended:
The blogosphere also has these geeky comments, should the above steps also fail.  I have tried these, but failed to find the file /etc/inet.d.  And one of the steps, "rebooting into 'recovery' (implying Rooting the phone) is a scary.  In any case, this is of some interest and may aid in further research and with this said, I am not recommending these ideas. 

Using app-store app "es File Explorer File Manager"
If you have troubles installing due to "Package File Invalid", repeat the steps above and attempt the install again.  You should be able to install at least one app at a time.

Launch "es File Explorer"
Press and hold the task-switcher button; this brings up the menu
Click Settings
File Settings, "[x] Show Hidden Files

Open folder /etc/init.d
Locate and delete file  01dalvik
From the Settings menus, Manage applications,  Erase cache and data from the Google Play/Android Market App. 
Then reboot into recovery (unclear on what this step implies)
Wipe dalvik cache, then wipe cache.
It will take a while for the phone to boot.