Why is my site missing from Google?

[stevel]

My Site apperas to have completely disappeared from Google's listings. However, the home page has a PR5 and if I do a search site:www.mydomain.com over 7,000 of the pages are showing up with correct titles and descriptions. Most of these pages have PR3 - 4.

My logs show visits from Googlebot but no referers. If I do a search for the domain name only I get one listing - the domain name itself but without the www i.e. [mydomain.com,...] and no description.

Does anyone know what's going on here?

thanks!