I agree with Anatoly that the yahoo.com feed does seem to be struggling through problem after problem. The good news is that yahoo does after a while fix these problems - and some of the recent filters provided by Anatoly as patches are no longer needed.
Unfortunately the latest feed problem for some data not downloading is becoming more widespread (and incidentally I have been unable to download the dow jones index '^DJI' for many months from yahoo!)
In my case I get around the download problem by sorting the updated psm download by 'last update' column (which groups the non updated shares together) then change the feed to yahoo.uk and 'update this selection' group again.
The yahoo.uk feed does not seem to have the download problem although it is much slower than the US feed.