Let me give brief information about 404 or other error pages.

If you do not see a page online and it gives error page:
1 – It can be page somehow broken, let your designer know in your email with a link ( which page you click on it, such as http://www.photoshopbrush.biz/brushes.htm , so he or she knows where to look) quickly, After examining  the situation and  it can be fix.
2 -  It can be the server is updating itself. Hosting companies do update their servers, at that time, no one can reach a page or entire site.
It  usually takes 15 minutes, wait a little bit, refresh the page then look at it. You may read newspaper entertain yourself.
3 – It is possible that, I am ( your web designer ) updating the site, adding page etc. If that is the case, when I am logged in, you may not see the pages. Sure you can wait for a while, drink a coffee , come back online, refresh the page, then look at it.
4 -  Here is the most important question: Is your computer online? Is your internet working properly? If you are not online, you will not see any page anyway. Make sure your computer is online, then scream about “what happened my page!” In that case calm down, send the page information to your web designer with a nice manner, not whining mode, nor “how dare you attitude”. Sure designers like to hear feedback from their clients. Just be nice, the life will be worth to live again.
5 – Guess what, your web designer made a mistake, and the page is not there. It happens, all you have to do, let your designer be aware the situation. It can be fix quite easily, no big deal.
6 – If you did not see a page online, maybe that page is removed. Are you sure it supposed to be there? Large websites contain a lot of pages, some of them gets old and removed from the site. Try to remember did you wanted that page be online, or did you ask your designer to remove that page a long time ago?
7 – If you can not see the entire website online: Are you sure you paid domain fee? If you did not pay your hosting or your domain fee on time, your page could disappear forever.  To be make sure, check your domain expiring date! You can click here to learn: http://www.designbynur.com/whois/whois.php
8 – If a page takes too long to open: It can be page full of images, too long text, of heavy content such as movie, flash or music file embedded.
You may need to wait patiently to see entire page download.
9 – Sometime pdf files takes long time to download, in that case, if the file is big, you just have to wait for download. Usually if the pdf created with photoshop, lots of graphic content in it, it takes long time to download. Text files always act quicker for downloading.

10 -  You were trying to look at a page online and it was not working. Before calling your web designer make sure the page it is not a cached on your computer. Wait  two minutes, refresh the page, then look at if the page is there or not. To do so:

  • To reload a page and bypass the cache:
    • either: Hold the Ctrl key, and press F5.
    • or: Hold the Ctrl key, and click the Refresh button on the Start bar.

    To completely clear the cache: ( Internet Explorer 8 ) Click “Safety” and select “Delete Browsing History”, make sure “Temporary Internet Files” and “History” is checked, then click “Delete”. If you want, you can also opt to delete cookies.

  • Read more about clearing your cache on your computer here:
    http://en.wikipedia.org/wiki/Bypass_your_cache

You may read these website errors time to time.
Some common status codes are: ( HTML code numbers)
The 404 or Not Found error message is a HTTP standard response code indicating that the client was able to communicate with the server but the server could not find what was requested. 404 – the requested page doesn’t exist.
401 – Unauthorized: Access is denied due to invalid credentials.
503 – The server is temporarily unavailable.
403 – (Forbidden) – The request was a legal request, but the server is refusing to respond to it. Unlike a 401 Unauthorized response, authenticating will make no difference.
204  – No Content – The server successfully processed the request, but is not returning any content.
300 – Multiple Choices – Indicates multiple options for the resource that the client may follow. It, for instance, could be used to present different format options for video, list files with different extensions, or word sense disambiguation.
400 – Bad Request – The request contains bad syntax or cannot be fulfilled.
408 – Request Timeout – The server timed out waiting for the request.