TheBigK - 7:21 am on Jan 13, 2013 (gmt 0)
Thanks a lot for your reply, @raymondcc. It's already 4th month for us after the errors have been fixed. Google's dropped 404 errors from GWT and the site's clean. In our case, the traffic dropped overnight, as the error count shot up from 7k to 17k and then to ~36k.
I must mention that we never were hit by Panda or Penguin. So, would you still suggest a time-frame we should be looking at? Or should I really continue to look for possible sources of problem?
How many weeks are usually 'several weeks' in Google's calendar?