I am worried that I may have picked up a virus on iTunes.
After downloading some music I found that iTunes in the Dock wasn't responding. Not only that, when I tried opening it in Applications the screen froze and seemed to be covered by a "black curtain" telling me to reboot. Funnily enough, after rebooting my other applications didn’t appear to be affected. I tried trashing my version of iTunes, but kept getting the "black curtain" effect and having to reboot. So I copied a friend’s version of iTunes which works fine for playing music, but I can’t burn CDs. Whenever I try burning a CD, whether through iTunes or through the Disk Utility, I get the same “curtain effect” and
have to reboot. I can play CDs, but whenever I put in a blank CD I get the "curtain effect". I am worried that firstly I won’t be able to burn any more CDs and secondly that if it is a virus it may affect other parts of my iBook. Can anyone help, please?

You might want to try trashing the songs you
downloaded, or convert them into another format,
especially if it only happens with certain ones..
Certain sources have been known to include
'ringers' in the P2P song file lists that can cause
problems - apparently to try to curb the excessive
growth of music file-sharing..although the black
screen one i've not seen before..
Just a guess...
Afterwards re-install your iTunes from scratch...
(Free download from Apple's website)