Everytime i open my msn messenger i get a request to download ADSAdClient31.dll from http://rad.msn.com/ADSAdClient31.dll?GetAd=&PG=IMSLB2&AP=1007
is it something suspicious i mean it appears to be from MSN website i downloaded it already and did a small research on the internet about it but didn't appear to be suspicious however even if you download it, it will keep poping
I just received and canceled it a few times, I have no idea what it is. Most probably a hot-fix or something but I wouldn't download it until it's been confirmed what it really is.
The ADSAdClient31.dll is related to that little advertisement box near your photo in Windows Live Messenger. It usually pops out when something related to it is corrupt in IE or Firefox. Close all browsers, keep on chatting. Does it appear any more?
Yea i got the same problem today, it's from the ad in msn, I updated my msn few days ago, and started getting that problem, it's annoying sometimes, but i'm too busy to figure it out.
You can edit the host file in the Windows folder to disable ads. That'll stop it from popping up again.
First result off Google shows it's a virus.

It may not be true, however one thing is sure is that it's been around since 2005 at least. It should be widely documented. Do your research and don't hesitate to share the results here.

Good luck :)
@Rahmu, Microsoft support has a thread on their pages for this. They say it's a corrupted file, and disabling the ads will stop this from keeping to pop up.
weird i started my computer now and it stopped from popping and i didn't do anything