Chances are, it's a timed pop-up. or, there's an 'adbot' that will 'pop up' this ad everytime you log onto RCU.

it's not RCU, it's probably your computer.
also, don't click on 'YES' or 'NO' as it';ll jsut confirm it either way. Click on the little 'X' at teh top right corner of the "request to install software"

Internet marketing strategies are sneeky, and rely on people ignorance, those who don't really know.. These 'adbots' get installed and track your 'internet surfing' habits. It then reports these finding to teh marketing co. who will then cater an annoying ad campaign tailored just for you.. Which you get. and get. and get. and get..

the 'gator corp.' , 'gain corp', and 'Quick time' are notoriously bad at this...

Get an 'adbot / spybot remover' such as 'Ad Aware' or 'Spysweeper' (freeware versions)
install it, and run it. You'll be surprised at what you'lll find!
Run it monthly, or weekly, depending on how you feel / surf..

Also, get teh 'google tool bar' as it'll block most pop-ups.