PR after update but all indexed pages gone

[StarkReality]

I don't know if it's a new problem, but I experienced the following for one site:

The domain was registered half a year ago, was never registered before, and the site got a PR4 on last update. At the same time, the day after the PR showed up in the toolbar, all indexed pages completely disappeared from google, including the root page.

So, it looks like the site was kicked, but it got fresh PR, which is the same on all datacenters.

I didn't have loads of supplementals, no duplicate content, no visible penalties, no hijacking. The site was fully indexed and suddenly it's gone from the index.

Any ideas what may cause this or anyone experiencing the same? Giving a site PR and removing it at the same time is a contradiction, isn't it?