Zivush - 12:27 pm on Mar 15, 2012 (gmt 0)

Here is official Google webmaster world post about:
"Do 404s hurt my site?"
[googlewebmastercentral.blogspot.com...]

some quotes:

404s are a perfectly normal part of the web... If some URLs on your site 404, this fact alone does not hurt you or count against you in Google’s search results. etc etc