Website Redirects to Install.php

Hi, my website redirects to wp-install.php often. Then automatically restores after around 20 sometimes 30 minutes. I have gone through many forums, found various options as follows:

> change database password – done
> optimize tables (check tables and click on with selected and choose optimize) – done
> installed w3 Total Cache plugin – done

but problem still exists.

Couple of months ago, I changed hosting. Downloaded database files, and WP files. Set them on localhost, made site run on localhost and then uploaded to new host.

It was working fine but suddenly around 2 to 3 weeks ago, it started redirecting to wp-install.php page. It also sometimes gives Error Establishing Database connection but when page is reloaded, it works fine.

Pls anyone help on this. I am stuck for long time on this error.

Also in database (phpmyadmin), sometimes this message is shown:
#1226 – User ‘pucom_pucom1’ has exceeded the ‘max_questions’ resource (current value: 75000)

Website Link: poemsurdu.com