Sorry, but ... is blocked on this network.

If you are unable to sign in to Yahoo! Web Messenger, you may see an error message such as "Website Blocked" or a notification explaining that your login credentials are incorrect.

If your computer does not meet the minimum system requirements, the browser may not be able to display the page at all.

Confirm that your computer meets the system requirements and that the Yahoo! Web Messenger website is not blocked on your network, and confirm that your password is correct to sign in and begin chatting online. No Account
To log in to Yahoo! Web Messenger, you must have a Yahoo! account.
This enables your friends to add you to their contact lists and chat with you.

It also gives you access to other services such as Yahoo! Mail.
To create an account from the Yahoo! Web Messenger page, click the "Get Started" button, and then click "Sign Up" on the following page.

Provide the requested basic information, including your name and birth date, and select your desired username and password.

Incorrect Password
When signing in to Yahoo! Web Messenger, you must provide the password that you selected when creating your Yahoo! account.

If you provide an incorrect password when signing in, Yahoo! Web Messenger displays the error message "Invalid ID or Password."
Click the "I can't access my account" link at the bottom of the sign-in screen.

On the following screen, click "I forgot my password" and then click "Next."
Follow the prompts to verify your identity and reset your Yahoo! password.

System Requirements
You may see errors if you attempt to use Yahoo! Web Messenger on a computer running an older operating system such as Windows 2000 or Millennium Edition, as Web Messenger requires Internet Explorer 6 or newer. Mozilla Firefox, Opera and Safari are also officially supported.

If you have confirmed that you are running a supported browser, navigate to the Adobe Flash Player page at adobe.com/software/flash/about.

The screen should display the message "Adobe Flash Player Successfully Installed."
Download and install Adobe Flash if you do not see this message.

Website Blocked
If you receive an error message such as "This page has been blocked" when you attempt to access the Yahoo! Web Messenger page, your network administrator has elected to block the website in the network's firewall.

Parents can also use home routers to block websites.
Ask your parents or network administrator to remove the block so you can use Yahoo! Web Messenger.
http://www.adobe.com/software/flash/about/

Your Outlook settings work fine at home, sending/receiving mail. You're on the road now, and you can no longer send, but only receive mails. You're getting an Error 530 or Outlook error 0x800CCC78.

The problem is the on-the-road ISP may be blocking port 25, and/or your ISP might not accept mail being relayed from other network domains. SBC Yahoo allows you to change your SMTP port from 25 to 587. Most ISPs let port 587 flow through. Internet access works, receiving email works, you just can no longer send.

Solution:

• Go to Outlook, Tools, Accounts, Server, Advanced, and change the SMTP port from 25 to 587. Hit Apply, OK, then exit/restart Outlook.

• Start Outlook, create a test email and send it. Should work fine.

• The solution might vary with other ISPs. Your home ISP must support an alternate port for SMTP TCP traffic, and the current ISP providing you access must not block that alternative port.

• Recognize this is all the fault of spammers and the ISPs trying to slow them down. This is why they block port 25 for non-customers.

If this doesn't work, just change the port back to port 25.
Alternatively, as with SBC Yahoo mail, you can always use the Webmail interface. This, like all other web pages, uses port 80, which ISPs do not block.

Not knowing whether you are in company or at home. If your network blocking Yahoo! Messenger service port, you can't get logged in.

If being blocked, use KarooLark web Yahoo! Messenger at http://karoolark.com/#yahoo

In company office? Your network might block you for using Yahoo! Messenger by blocking its port.

If you are blocked, you can use web messenger instead. e.g. http://karoolark.com/ web Yahoo! messenger

Similar "can't sign in" problems may be caused by your company/school network. Lots of networks may have firewall blocking instant messaging services.

If you are blocked, try to use KarooLark web Yahoo! messenger: http://karoolark.com/#yahoo . It also supports other web messengers too.

For the beggining try to sign in from the webinterface: Yahoo Mail. If it works, then changing connection options for your messenger. It could have changed. If it doesn't work try to reinstall Yahoo Messenger. Good luck.

Here is what worked for me:
Make your IP static. Watch this video if you don't know how.
http://www.youtube.com/watch?v=rspWwGqmsWI
and use 8.8.8.8 as the DNS

Are you using Internet access supplied by your employer, or by your school?

If so, then contact the Network System Administrator at your work/school, and ask them to verify that they have chosen to block access for all their employees/staff/students. It is "their" network; so, they can block whatever they want to block, because you clicked "I Agree" to their Appropriate Usage Policy, in order to access their network.

Mozilla Firefox has the ability to block content and images from web sites. If you're seeing a white screen when visiting Yahoo! Mail, or clicking the "Save to My Web" button or other toolbar buttons , you have either accidentally or intentionally blocked images and/or content from yahoo.com. Check your Mozilla Firefox and Extension options to make sure you haven't blocked yahoo.com or accidentally blocked images, iframes, etc. via a wildcard.
If you have AdBlocker installed,

1. Click AdBlock under the Tools menu.
2. Click Preferences.
3. Remove any entries from the blocked sites list that contain "yahoo.com" or "yimg.com".
4. Click Done.

If you don't have AdBlock installed, check your Firefox options:

1. Click Options under the Tools menu.
2. Click Web Features.
3. Click Exceptions next to Load images.
4. Remove any sites listed that contain "yahoo.com" or "yimg.com".

If you still don't see the Download button, either your user profile is corrupt or you have another extension installed that is blocking images from Yahoo! Please a new profile or try running Firefox in Safe Mode. In addition, see the Mozilla Firefox FAQ link under More Help.

check for any firewal or else u have blocked the yahoo mail login page accidently...