Phil, I would say that my conversions with them have been weak but not to your level... 1:2000 (their count) is about the number for the last 60 days.  It is enough that I am working "optional" traffic in other directions for now, waiting for things to get better.  I haven't seen anything particularly wrong, just one of those things, I guess.
I can wait for them to get better.  
 
Alex