Why am I getting a Yahoo Mail Error?

Why am I getting "Error 999" when I try to check my Yahoo mail?

• Okay, so I've been logged into Yahoo all day and I've checked my email about 5 times today with no problems. I was setting up a new DeviantART account and was supposed to check for a confirmation email. I literally checked my email less than five minutes beforehand with no problems, but when I checked for the conformation email, I got an "Error 999" message. I've tried about a dozen times since. I've logged out and back in, restarted Firefox, but I still keep getting "Error 999" when I click "mail". I can log into Yahoo no problem it only happens when I click "mail". I really need into my email so I can confirm my deviantART account. Any suggestions as to what could be the problem?

• Answer:

  Clear the cache of temp files and cookies, restart the computer. If that doesn't work, sign out, shut down the computer for a few minutes. When you turn it back on, turn off the modem for a couple of seconds to a couple of minutes, when you turn it back on, sign in and it should be cleared. If not, you will have to wait for a time. Sometimes a couple of hours or more. This is just a code that Yahoo puts when the problem is unidentified. It's generic