TheBigK - 8:48 pm on Nov 27, 2012 (gmt 0)
Lysis (who seem to be Top Contributor at Google Webmaster Forums) has said that thousands of internal 404 errors won't affect rankings.
Every single thing I determine as 'problem' is shot down by the 'experts'.
There's another webmaster I found on the Internet who said his website had massive internal 404s and it took him 4 months to recover. But according to Google, it's not a problem!
@TMS: My graph pretty much remains the same these days.