Rankings Returned

It is very hard to understand what is going on with Google page rank at the moment. This website changed from 6/10 on the home page to 2/10 across the entire site. In the past few days it has reverted to 6/10 for the home page. The cached snapshot of the page is from a different domain.

There is obviously a fault in the Google indexing system or it is being hijacked? I cannot understand how this has happened and I believe there should be better controls in place. There is no reason or excuse for a pgae from a different domain to appear in a cached result.

It raises many questions and to make matters worse the domain that hosted the page that has been cached is dead. If you have any clues please fill me in, I am confused.