my guess is this is just another example of yahoo running out of money. the company can't maintain its portfolio tracking system. sometimes it works, sometimes it doesn't. some funds aren't updated for hours. it'd suggest migtrating to morningstar. yahoo is checking out.
All internet companies -- even the good ones that are surviving and will survive -- are going through an abrupt change. There are staff layoffs at AOL, at Ebay, at Yahoo. Sometimes, it ain't smooth baby. That's all you're seeing -- the rough corners. Means nothing. Ya wanna see glitches -- go the Ebay.