Hmm, that's odd. I've never used Silverlight so I wouldn't really know
The only thing I can suggest is to check your configuration settings in RealPlayer (Tools>Preferences>Downloading & Recording and it should all be there for you to sort out), check you have the most recent RealPlayer, and if you can, switch off or disable Silverlight for the time being (I'm not sure how Silverlight works so I don't know if that's even possible).
Otherwise just send me the link to whatever you want to record and I'll see if I can do it. It COULD also be possible that the player on the KROQ site is a different sort of player that doesn't allow for ripping, much like the ones on imeem and last.fm. However, when I go on the KROQ site the little live broadcast player at the top lets me record it. I just don't know what to click on to get to what you want to record. So like I said, try my suggestions, and if that doesn't work just tell me what to do
EDIT: I see your problem now. I just managed to get on the page you wanted and the problem is that the video is a Silverlight streaming which is very annoying indeed, as RealPlayer won't be able to capture it. First see what happens when you click on Silverlight Configuration; it might give you some options for ripping and downloading. If not, then there is software which you can get for free as a trial version here
, althought it might be a bit of hassle considering you only want to use it once but it's an option. That software, I think, allows you to rip .wmv format videos, which you can then convert into whatever you want. I haven't actually tried it so please don't take my word for it.
EDIT AGAIN: There is a good chance that someone else here might do it, and even if they don't, it will probably end up on YouTube in which case anyone can rip it, even if it is lousy quality.