Problem: leaving membership query statement empty causes havoc

I have SMS 2003 with collection A and B.

Collection B is limited to A, as well as contains a query statement that
contains variables so that only resources with specific pc names get imported
from A.

Collection B is being phased out, so I remove the whole query form the
statement, leaving it blank. I click OK and update the collection membership,
and see that there are now no more pc's in Collection B. Excellent.

I come back the next day, and see that all collection A pc's have been
imported into B. And so all the advertisements that used to apply to B
reources, have now been applied to A's resources too.

I go into the porperties of B, and see that there is the following entry in
the query statement:

??????select
SMS_R_System.ResourceID,SMS_R_System.ResourceType,SMS_R_System.Name,SMS_R_System.SMSUniqueIdentifier,SMS_R_System.ResourceDomainORWorkgroup,SMS_R_System.Client
from SMS_R_System inner join SMS_G_System_COMPUTER_SYSTEM on
SMS_G_System_COMPUTER_SYSTEM.ResourceID = SMS_R_System.ResourceId ??????

It seems that, although sms allowed me to save a blank query, it then went
and put in a query without variables. What went wrong here?
Surely leaving a query statement blank should mean that there ishould be no
resources imported?

Would greatly appreciate if someone could shed some light here, as the
application of the incorrect advertisements has had a severe impact on our
business.

Thanks