Sorry, there's nothing in about:config to hide those blocked ads. Adblock Plus has a preference for "collapse blocked elements", which is what I use to block ads.

You might want to ask about that issue over at the ABP forums. http://adblockplus.org/forum/

Thanks, ed...I'll try over there, too!

Quite simple and should be more widely known:

type about:config into the address space.

Navigate to browser.xul.error_pages.enabled

Click on it to change the default 'true' to 'false'

Problem neatly solved... Simple and elegant...it need not have taken the half hour googling around to find it. The answer should have been known right here.