recurring message stating i need to install of fix config file

for the last 3 days my site keeps going down. I check in the morning its fine, check later in the day get this message:

Hello. Thank you for loading Zen Cart®.

You are seeing this page for one or more reasons:

This is your first time using Zen Cart® and you haven't yet completed the normal Installation procedure.
If this is the case for you, you will need to upload the "zc_install" folder using your FTP program, and then run zc_install/index.php via your browser (or reload this page to see a link to it).

Your /includes/configure.php and/or /admin/includes/configure.php file contains invalid path information and/or invalid database-connection information.
If you recently edited your configure.php files for any reason, or maybe moved your site to a different folder or different server, then you'll need to review and update all your settings to the correct values for your server.
See the Online FAQ and Tutorials area on the Zen Cart® website for assistance.
Additional Details: includes/configure.php file contents invalid. ie: DIR_FS_CATALOG not valid or not set

To begin installation ...

The Installation Documentation can be read by clicking here: Documentation
You will need to upload the "zc_install" folder using your FTP program, and then run zc_install/index.php via your browser (or reload this page to see a link to it).
The Online FAQ and Tutorials area on the Zen Cart® website will also be of value if you run into difficulties.

I clear all my browsers and restart my computer and it's back again. I have not changed any configuration files nor have I added any new add-ons, tools, etc. And part's of my "tools" section keeps giving me "File not Found" errors such as:

Admin Settings: The requested URL /JBMadmin1b2/FILENAME_ADMIN.php was not found on this server.

Email Welcome: The requested URL /JBMadmin1b2/FILENAME_EMAIL_WELCOME.php was not found on this server.

here is my server/phpversion, etc info
site: http://jolenesbooksandmore.com
Server OS: Linux 2.6.18-238.19.1.el5PAE Database: MySQL 5.0.92-log
Server Date: 07/21/2012 20:18:59 Database Date: 07/21/2012 20:18:59
Server Up Time: 20:18:59 up 60 days, 18:30, 0 users, load average: 4.97, 5.92, 6.55 HTTP Server: Apache
PHP Version: 5.2.17 (Zend: 2.2.0) PHP Memory Limit: 64M PHP Safe Mode: Off
PHP File Uploads: On Max Size: 32M POST Max Size: 33M
Database Data Size: 1,416 kB Database Index Size: 771 kB

Sorry, I know this is a lot of information but would appreciate any help to fix these glitches.

jolenemacinjax:

Additional Details: includes/configure.php file contents invalid. ie: DIR_FS_CATALOG not valid or not setMeans the paths in your /includes/configure.php file are pointing to folders that don't contain Zen Cart files.
jolenemacinjax:

part's of my "tools" section keeps giving me "File not Found" errors such as:

Admin Settings: The requested URL /myadminfoldername/FILENAME_ADMIN.php was not found on this server.

Email Welcome: The requested URL /myadminfoldername/FILENAME_EMAIL_WELCOME.php was not found on this server.
Whenever it displays a placeholder in UPPERCASE LETTERS, it usually means that there's no definition for that value getting loaded. ie the file that contains the define() statement for that placeholder (called a "constant") isn't on your server or isn't getting loaded properly.
In the case of FILENAME_ADMIN and FILENAME_EMAIL_WELCOME that's because those were removed in v1.5.0 and are no longer used. So, if your admin menu is trying to find those, then that means you're using v1.3.x admin code instead of v1.5.0 admin code. You can't mix them up. If you're going to upgrade, you have to upgrade completely, not interchange them.