Yahoo! Account Problems

Introduction

Old Problems, New problems, Security Measures and crackers have meant that many people experience problems whilst using, or attempting to log into their Yahoo! accounts.  This page aims to explain some of the problems, and more importantly how to solve them!

Problems

Your account has been locked for security reasons
You have logged in on a different machine
Incorrect Username or Password

Your account is locked for security reasons

This happens because somebody tried to make a large amount of attempts to guess your password and enter your account.  Many times, it's not actually someone trying to access the account, they just know that by sending a huge amount of requests, they can cause the user problems by having their account closed.
The servers understand that a human can make about 5 or 6 attempts a minute, this would be normal if you had forgotten your password or made a typo etc...  and at this rate, it would take 18011 years to guess your password.
An automated program however, could make 1000s of requests a minute or even more!  Its when the server experiences these numbers, for your own security, it locks your account.
Fix:
First, visit http://login.yahoo.com/config/login Don't Worry! The first attempt will fail, say incorrect password or something.  It's the second attempt that matters.  What you will see this time, is that you have a word verification.  This is a secure system by which only humans could be making the request, bots cannot see the text, they see encrypted numbers.
For some, this is it, the account will log in again!  For others, it's not so.  You have to wait up to 48hrs for the account to come back.

You have logged in on a different machine

You can only log in once with your ID.  If you have ever logged in on messenger, then logged the same ID in a client, you might have seen Yahoo! Messenger say this message.  But for many it happens just as an error.  If you are suspicious of someone knowing your password, they might have logged into your account, but if you have a secure password only you know, it's most likely an error.
Fix:
Some users can log straight back into Yahoo! with no trouble.  Others will keep getting the message after a few minutes online, others can't log in at all.  If you one of those first people, you're ok now!
If not, you just need to make sure your completely logged out of messenger.  Log into http://login.yahoo.com/config/login then log back out again (Sign Out) upper left.  You should now be able to log into Messenger.

Incorrect Username or Password

Ensure: Firstly ensure that if you have messenger set to auto login, you disable it and re enter your username and password.  Use login>>change user.  This will bring up the login screen with the boxes.  Clear them and start again.
Fix1: Follow the instructions for Your account is locked for security reasons.