Yes, if you are using a free app, it might be ad supported - that's the most likely reason. Or maybe the site you are using has pop-ups that aren't stopped by the pop-up blocker. This is adware, not really malware.
If Adchoices is showing in the PlayBook browser, you could try one of the third party browser apps. There is one called Secure Browser that I think can block ads.
https://appworld.blackberry.com/webs...countrycode=US