Precious metals are a notoriously volatile asset class, and many factors affect the price. But some observers are convinced that the gold market is subject to massive manipulation by the 'bullion banks.' Here's a video that summarizes this view, produced by an organization committed to exposing and combating such practices:
http://gata.org/node/20
Of course, not everyone holds this view. In fact, an interesting debate on this topic will be held at next month's Hard Assets Investment Conference in Las Vegas:
http://gata.org/node/6484
When will the present downturn reverse itself? No one knows for sure, but prevailing opinion in hard-money circles is that the 'gold bull' will resume its charge sometime this fall. Short-term movements don't alter the fundamental reality that appears to bode well for PM in the long run (i.e. continued runaway spending by the US government, further printing of $ to cover the shortfall, the resulting devaluation of the dollar, an economy plagued by various crises, geo-political uncertainty, etc.).