website keeps going down overnight

My website overnight and in the early morning hours frequently stops working and gives me the following error message:

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, [email protected] and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

does anyone know what is causing this or what can be done to fix it.

I am now seeing the following error when i try to access the page:

0 DB_ERROR_NOT_CONNECTED
in:
[select * from project_version WHERE project_version_key = 'Zen-Cart Database' ]
If you were entering information, press the BACK button in your browser and re-check the information you had entered to be sure you left no blank fields.

Looks like this is a problem on your provider side (most likely a DB problem) or the server is exhausted. If the problem persists for the next few days, contact your provider.

Early morning hours are typically when various software maintenance is done on the Server. This can put a high load on the Server and if too high, things will stop working till the maintenance is done. Suggest you check the Server load from within your Hosting Control Panel, just before the problem usually starts. And depending upon the Control Panel, you might be able to check Server load when your other scripts are not working.