My connection, what causes this?

On my dial up, ever once in a while when I hook up, no web page will load nor can I receive e-mail.

When it does this I can click on my connection status, the sent Bytes will be higher than the received Bytes, which it should be opposite of that.

This computer has a U. S Robotics 5610B.

And I have got on my other computer, which has the original modem in it as well as a U. S. Robotics 5699B and it will do the same thing on both modems on it.

On a recent Saturday it was this way from about 9:30 AM till about 10:45 PM.

I have asked my ISP about this and they ask questions like this, do you have an anti-virus, do you have anti-spy ware to check for sypware on your computer, how often do you boot your computer, how long is your phone cord.

Do you suppose this might be a problem on my ISP's end and they just don't have an answer?