Strange problem with ZenCart

[IronMan101]

My problem is that for the past few weeks i've been setting up a shopping cart on my website (using the Zen Cart) module and I've been able to successfully access the admin login screen - Until Now...
Whenever i enter: www.example.com/admin OR www.example.com/admin/index.php - I receive the following error:
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Not Found

The requested URL /admin/zc_install/index.php was not found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
Apache/1.3.37 Server at www.example.com Port 80

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The address to the admin's login page has not been changed by me and certainly should not be located in zc_install - as I was asked to remove this directory after a successful installation.
The Not Found error has only recently appeared and I've already tried looking through the files using SmartFTP but I haven't found anything that looks odd and that may be the cause of this problem.
Anyone able to help me or to tell me what i'm doing wrong?

[DrByte]

You've damaged your /admin/includes/configure.php file.
If that file is missing or contains "default" information, instead of information that allows access to your website's database, then the admin will look for the zc_install folder because since your configuration is invalid it figures you must be wanting to install.

[IronMan101]

The file isn't missing and I've already checked it. The information seems correct and I have not tampered with the file at any one time. Is there a way to fix this or will i have to reinstall?

[DrByte]

What permissions are set on your /admin/includes/configure.php file?
If the permissions are set too low, then the server won't be able to read it, and thus will think it doesn't exist.

[IronMan101]

Permissions for that file are: 444
User - Read Only
Group - Read only
Others - read only

[DrByte]

What version of Zen Cart are you using?
Have you renamed your admin folder ?

As mentioned earlier, the only reason the admin would point to zc_install is if the configure.php file cannot be found where it's expected ... namely at /admin/includes/configure.php

If the file exists in the proper location, then the only other reason for it not being "found" is if access is denied to it ... which could be caused by the file having too restrictive set of permissions, or an ownership problem preventing it from being visible to the apache webserver processes.

You may need to ask your hosting company for assistance.

You said earlier that you had changed nothing. If you haven't made any changes, then it would be logical that someone else has changed something. Maybe the hosting company changed a server configuration somewhere which is breaking your access? Another reason to ask them what's been happening on the server of late.