JS_Harris - 1:34 pm on Mar 24, 2009 (gmt 0)

To disprove this idea I offer the following. If it was true we could go enter the domain name of any site we hate and they would be removed. Since we know, as Google tells us, that it's not possible to hurt another sites rankings it must be false.

But "something" has happened. Perhaps Google gathered your traffic details and found that you visited every page before the direct traffic came from each of them? not likely. Perhaps your sudden spike of type in traffic triggered a filter since it's unusual? Plausible but also unlikely. Perhaps you've been filtered since the traffic is all from (most likely) irrelevant content pages? Getting warmer...

It's safe to say that the "quality" of your traffic took a nosedive and that the ratio of type in traffic vs link in traffic changed dramatically. Wait a few days and see where you stand in search results, a day isn't long enough for a test.