I have had the same problem on two of my computers running Win 2000. When I loaded Limewire, McAfee stopped working. Similarly the scheduled tasks icon no longer loads on start up. While I can get McAfee to work by opening the program and starting the virus scan, the scan no longer works in the background.
When I start McAffe, I get a warning message noting that "Vshield is not loaded, would you like to start it now" but it does not start when I click yes.
Sadly, uninstalling Limewire and McAfee and then reinstalling McAfee has not solved the problem.

Does anyone know of a fix? I am not a programmer, but would like to get my computer back to its previous state.