Getting Rid of a Banner Ad That Follows Me Everywhere?

How do I get rid of an incredibly annoying banner ad that seem to appear on almost every web page I open? Has anyone seen these Ads?
It's a flashing ad with a blue border and a yellow smiley face. It announces "Congratulations! You've Won!"
There's a grey background and it also states THIS IS NOT A JOKE - YOU ARE THE 100,00TH VISITOR!
Click Here! It's actually on this very page as I write this. It seems to follow me everywhere. Does anyone out there know how to get rid of them ?
It seems to appear in greater frequency on just about every single web page I open on every website.
I can't seem to rid of it.
It's really annoying.

If you're using Safari...do you have "Block Pop-Up Windows" enabled?

- Nick

NOTE: Thread moved to appropriate forum. Not just anything goes in Anything Goes

Try clearing out your browser's cache and cookies. Follow the following steps depending on your browser

1. Safari: Safari > Reset Safari...
2. Chrome: Chrome > Clear Browsing Data...
3. Firefox: Tools > Clear Recent History...
4. Opera: Tools > Delete Private Data...