Cannot list group members - AD security restrictions? Help!

Hi all,

I am just struggling with a bug which emerged after moving my asp.net
application to another server.
The server came preinstalled, probably with some security modifications. I
can query list of users only from domain security groups I belong to.

Example:
(&(objectCategory=person)(objectClass=user))
- correctly returns all the users

but:
(&(objectCategory=person)(objectClass=user)(member Of=CN=Instructors,CN=Users,DC=berndson,DC=org))
- returns nothing, although Instructors has members (I am not one of them)

When I add myself to the Instructors group I can immediately see all the
other members.

This must be some security feature/setting specific to the server (2008 R2,
domain controller).
On the other server (2008 R2, stand alone) the problem does not exist.

Could someone, please, point me to the right direction before I pull all my
hair out.

Thanks

Thomas

I did more testing.

It looks like AD query does not return all the group users only when I open
my asp.net application in browser directly on one of the servers where it is
installed.

In such case groups contain only myself - providing that I belong to the
particular group, of course.

When application on the same server is accessed remotely (with the same
credentials) everything works as expected.

It does not makes sense to me.

Thomas