when you loaded real one it asked if it could be the default handler you should have taken the tick out of the audio cd box. you need to find associations and then clear real one from the audio. I will look it up.
There's nothing wrong with Real One per se - it just needs to be told who's boss! As you've discovered, Real One, and other similar players, need careful configuration as they have a tendency to take over all your audio and video types. However, if you want to take advantage of all the streaming media that's out there you'll probably need at least Real and WMP, plus Winamp (my personal favourite for MP3 playback) and arguably Quick Time.
I gave up using RealOne,even if I cfg'ed it to "Only contact the outside world when its in use" it STILL took over my system.I now use RealAlt,it has an Opera plugin (that works) and never asks to breach my firewall.Get it here Its in the column on the left.click here
RealOne play is fine, but it needs a firm hand, you have to tell it who's boss. When you install it make sure you spend a little time going through all the preferences to configure it how YOU want it to work, not how it thinks it should work.
It sits in the backgroud for me now behaving itself.