Urgent Help With Query (Cross Join)

I have the following tables:
members
--------------
member_id
member_tpc_id ( = tpc.tpc_id)

tpc
------
tpc_id
course
------------
course_id
tpc_assignment
---------------------------
tpc_assignment_id
course_id
enrollment
-------------------
member_id
course_id
enrollment_status 
Now I want to select all members where member_tpc_id>0 and get the enrollment_status of each member in each course where course_id IN (Select course_id From tpc_assignment)
Now what i did was get all the members and then all the courses and did a cross join between them. There are about 1900 members and 80 courses and when I do a cross join I get 1900*80 rows (152000) and the status of each member for all the 80 courses. If not enrolled it returns Not Enrolled (i have a UDF which takes a member_id and a course_id and returns the status). The BIG problem is that its taking about 6-8 mins to run the query and as a result its timing out on the aspx page. Can someone please tell me how I can do what i am trying to do without using the cross join because I suspect its the culprit here. The query I came up with is 
Select
*, dbo.returnStatus(temp1.user_id, temp2.course_id) As Status,
(Select tpc_title From tpc Where tpc_id = temp1.member_tpc_id) As Tpc_Title
From
(Select member_id As user_id, member_name, member_tpc_id
From members Where member_tpc_id> 0 And organization_id = '1'
)temp1
cross join
(Select course_id As course_id, course_title As course_title
From course Where course_id IN
(Select course_id From tpc_assignment Where tpc_requirement_id IN
(Select tpc_requirement_id From tpc_requirement) And course_id<>0 And organization_id = '1')
)temp2
Order By member_name, Tpc_Title

Please help. Thank you.