Internal pages listed URL-only, Index page penalized

Site banned or some other technical issue?

[crobb305]

Over the years, it has been accepted that if you are "banned" from Yahoo, the site:example.com search will return only the index page.

But, I am seeing some sites that are penalized (not ranking for anything), but have some most internal pages listed url-only for the site: query.

Could this be indicative of some technical issue related to my site? I have read some speculation about having too many 404 errors served. Anything to this?

Any ideas?