I had the same and it took me so much work to loos ethe problems.
What happens is that if you start that play.exe in the mp3 window, you automatically download a prog to change your register.

After a few hours suddenly in explorer the most weird pages are opened.
this is getting frequenter every session.

it is very hard to loose the problem.
check these links to see how you MIGHT loose the problem:

http://www.pc-helpforum.be/f163/opgelost-nebuler-veiligheidsagent-9428/

http://www.pchelpforum.nl/viewthread.php?fid=43&tid=21644&action=printable


For me, I needed a recovery ;o)

ok, sofar my tip