Hi, All
"
I'm very grateful and all for your hosting, but some of my visitors gets a box that asks for thier password on my site when they try to download ." This is the message of our client.
Did this happend due to the day bandwith limitation(He didn't exceed his monthly quote)?
What can it be and where can i find information on this topic?

Thank in advance,

What are they trying to download? I'm sorry I don't understand what you're asking...

They are trying to download just files(from web-site).

So if I understand you correctly, your clients come to your web site and cannot download certain files? If that is correct, then first of all, I downlod files from your site just fine. But secondly, check maybe files they are trying to access are in a secure, password protected folder.. But then your statement about bandwidth limitations have no sense to me - if it is your web site - they cannot get this message since they are the ones who are downloading.

It can only happen if you exceed your bandwidth limit (if you are a reseller) and you parent host cut you off.

EDIT: Btw, Alex, I would recommend you to hire an editor to go through your web site, because it can be better. Many parts of writing are really hard to comprehend.

There is no secure access and clients are the visitors of our client(we are the hosting company and it is his web-site, not mine)

Do you have a URL to the page that is causing the password box to appear?

Check the same directory the download file is in, for an .htaccess file. If not one there then check the Document Root dir. -- same dir. as where the Home Page is.

This presumes you are using Apache as these Authentication requests only pop up when specified in an .htaccess file. If one is not appearing now and the one that appeared before was before the end of the month, it is quite possible the Control Panel does it automatically when either; Web space or Data Transfer for that month, has been exceeded. The Control Panel will also, automatically remove the restriction at the beginning of the next month.

I have one more question.
Does Cpanel have a day transfer quote(not monthly)?

Not that I know of. Been using WHM/Cpanel for a few years now and that option has been brought up, but never implemented.