TheOptimizationIdiot - 1:00 am on Mar 11, 2013 (gmt 0)
What phranque said, especially the first line.
And to say the same things in other words: If you're not linking to them, then give them the "ignore" cause in my experience they're not the issue, but if you do link to them, then fix the links you have pointing to those locations yesterday!
Me linking to 404 pages on your site should not cause an issue for you, but could very well cause one for me. You linking to 404 pages on your own site could cause an issue, but if you're not linking to the new 404s, then the problem with traffic is likely somewhere else and not the 404s you're seeing reported.