XP...I did download cooliris (shopping channel) and deleted it? If I try to open photos or thumbnail pics two twin arrows appear - if the cursor hits them I get the 'cooliris' shopping channel.
As Chuck says, if you installed it using Firefox, you can also uninstall it from within Firefox.
However, if you installed it from within Windows Explorer, you need to go to Settings/Control Panel/Add or Remove Programs, locate it in the list, and uninstall it from there.
It's not a virus - it's just a really awful piece of software.
Should also mention that if you just disable it in Firefox, it will remain on your computer and can still be accessed from the icon that it places on your desktop. My advice is to uninstall, rather than just disable it.