Hello 5mars,
I think you are trying to use Nero Showtime, nero burning rom, i agree with you, i have also faced this one, i use core 2 quad that has 4 logical processor but that too does not help me even, mcshield eats 25% in my case but that make nero to be not responding for about 30 seconds to 45 seconds, well i have found workaround for this, i have given up using Nero show time as using power dvd 9 and media player 12 for windows 7 and there is no such problem with additional windows 7 codec installed, i am telling you all these things so that you do not get in more trouble or figuring out anything else..For nero burning rom, try to update nero product as well check the archive or large file that you are trying to copy as well as if you think mcshield is hogging CPU, and your files are clean, than you can turn off mcafee for time period, but not from taskmanager plzz.