De-indexed by MSN?

[Kromvel-spring]

Greetings!
Recently I had a few problems with a few sites I just start to handle (all on same IP):
www[dot]pmoz[dot]org
www[dot]pro-board[dot]com
www[dot]jdhealthcare[dot]com
Recently they got de-indexed by MSN, for a reason that remains wierd to me. Even more a few other sites that linked to these ones (located on different IPs) received a penalty (drop in SERPS).
Do you have any idea why this happend - as far as I know the sites are legitim and no black hat seo is used.
Please let me know if you notice anything that may result in this MSN ban / penalty.
Thank you in advance.

[tamecrow]

What sites are linking to these? From what you're saying, you have a few sites that are all inter-linking. MSN will be able to detect this and treat it as artificial link development.