Liveperson image button and Plusnet

[#1]

Every time I connect to Plusnet using IE8 I find that their Home page downloads until things stop with a message
"1 item remaining. Downloading picture https://www.plus.net/liveperson/images/button/transparent.gif"
The picture never seems to download.
I also notice that a number of cookies are being added with file names such as "my-name@liveperson(1)".  I have deleted these but they seem to re appear when I next connect.
Does anyone know what this is all about please and whether it is sanctioned by Plusnet?
Also whether they are harmful or whether it is necessary to leave them on.
If not necessary, how can they be stopped ?
I have never knowingly had any connection with the Liveperson.com website (if that is the source).

[#2]

There's no problem there, it is sanctioned - liveperson handle the sales chat windows that sometimes pop up when you've been browsing the portal for a while. There shouldn't be any problem with the cookies (or deleting them, if you wish) but that's why they're there and what they're doing.
Hope that helps,

[#3]

Very helpful - thanks. Feel a lot easier now !!