digitalv - 7:48 pm on Mar 8, 2011 (gmt 0)
I think the problem is rather that you used "same anchor text" for all those links. Because I experienced a mega drop too with some keywords. After I adjusted their link profiles with more diverse anchor text (some with no ranking benefit whatsoever) I got back up. :)
Interesting, I wonder if time is a factor (a bunch of links at once vs. the same text but more naturally over time). Also curious how that would affect if the anchor text was your company name or service name (which it was in this case, and was in the page title).