Never seen it, and I use firefox. Are there actually still people who use IE. Upgrade it only takes a few seconds to download and install.

I've never seen those ads before either, but apparently 80% of the forums use Firefox.

I honestly can't remember the last time I saw an ad of any kind , the fox takes good care of me.

I just went into IE and surfed around, and never got one. Chances are one of the following is true:
1) You have adware on your computer somehow
2) You're ISP is one of the precious few that will go into your internet traffic and insert ads for you (source, second, and a few others that I will let you research for yourself)
3) a few other less-likely prospects than either of those. I don't think it's VGC based on my inability to trigger them, but I will keep trying.