Strange things leading to ban

[skymike]

I have 2 webservers, one hosting my main website and one hosting my mail server. The mail websever had a 301 redirect on to point to the main website. My website had a PR of 4 and the 301 site address had a PR of zero.

Whilst Google was running through its last update I had a problem where the PR values were switching between the two addresses..... how could this happen?

Afterwards, both became PR zero and all my pages dropped out of the index, I lost all Google status for most of my well ranked key phrases too....

Has this happened to anyone else?