"blue shield with question mark" - what is it?

[clockworks]

I keep getting this popping up next to my cursor on these forums. I've not noticed it elsewhere.
I normally run OSX, but I've been using XP SP2 on my Mac Mini for the last few days, and it's annoying me. It looks like the Windows update shield icon that appears in the system tray, but it's blue with a white question mark inside. I also get a "blip-blip" sound, but no text balloon.

[andrew1810]

Sounds like the Virus Protection notification, to turn it off:

Start - Settings - Control Panel

Click on Security Centre, then in the box bottom left press Change the Way Security Centre Alerts Me

Then just untick the box

[clockworks]

Thanks for pointing me in the right direction - I found a list of the icons in a FAQ a couple of levels down Security Centre. It's a "potential security risk notification" icon, and seems to be triggered by some of the adverts on this site.
I've turned off the firewall notifications (while leaving the firewall enabled), and hopefully that will stop it.

I think it's very stupid of Microsoft to have a warning icon flash up on the screen, then not alert the user as to what it actually means!

[clockworks]

I'm still getting this blue Shield icon. It now only happens when the "Sonos" adverts at the top of the page are loading.