Why is Yahoo mail giving error 999 sign and not connecting to my e-mail?

It seems that this is happening to a few people. I emailed their tech team and this was the response:

Hello,

Thank you for contacting Yahoo! Customer Care.

We're sorry you've had difficulty accessing Yahoo!. The error you

received is typically caused by unusual activity from either your

computer or your Internet Service Provider (ISP) to Yahoo!. While this

type of problem is usually temporary, if you continue to experience this

error, we recommend that you try the following suggestions:

1. Contact your ISP and let them know you are experiencing connectivity

problems with Yahoo!. You may have difficulty accessing Yahoo! if we

detect unusual network traffic coming from your ISP. Only your ISP will

be able to address and resolve this abnormal activity.

2. Check that you are not using any third party software program or

application to access Yahoo! services. Please keep in mind that these

types of programs are not supported by Yahoo! and may violate our Terms

of Service, and therefore may contribute to your receiving this error.

3. If you have not scanned your computer for spyware and viruses, please

do so now. Some spyware programs and computer viruses will run separate

programs on your computer for a variety of purposes, sometimes slowing

your computer down in the process, and even preventing you from

accessing certain Internet sites such as Yahoo!.

So it appears to be Yahoo itself.