unwanted banner ads in IE

[seakrait]

i've been getting these banner ads appearing in some (but not all) of the pages i view using IE/firefox.

i have microsoft security essentials installed and nothing else. ran some scans but nothing found. what else should i be doing? [/noob]

[SkinnyPupp]

http://malwarebytes.org/

[seakrait]

thanks! i'll give that a try. currently running ms windows malicious software removal tool but nothing found yet.