Google not showing sites linking to my site

"Your search - link:www.mydomain.com - did not match any documents"

[SanjayL]

Hi everybody,
I am having a site with good numbers of inbound links.
some of them are PR 4 and PR5. My site is having PR 0. Problem is that when i check sites linking to my site (i.e using link:www.mydomain.com) in google it returns Your search - link:www.mydomain.com - did not match any documents. While fewdays back it was showing links.

while for other searches like site:www.mydomain.com and "mydomain" it shows the links.

It still shows good no. of links when checked in yahoo and MSN. I have not used any unfair SEO.

So can anybody tell me whether my site is penalised by google and what to do now so that I can reslove this problem.

One intereseting thing i noted when trying with MSN,Yahoo and Google:
When searched with keyword "www.mydomain.com" all search engine are returning link to "http://www.mydomain.com"
But,when i search "mydomain.com"(i.e without www) , it returns my homepage with hyperlink to "http://mydomain.com" and not "http://www.mydomain.com"

I am comlpletely wiered..!
Can any body suggest me what to do?

Thanks in Advance
Sanjay