Your code can be attacked using a SQL Injection.
I would change this code
rsForums.Source = " SELECT * FROM (SELECT *, (SELECT COUNT (*) FROM REPLIES WHERE REPLIES.MSG_ID = MESSAGES.MSG_ID) AS REP_COUNT FROM MESSAGES, CATEGORIES WHERE CATEGORIES.CAT_ID = MESSAGES.CAT_ID) WHERE MESSAGES.CAT_ID = '" & fixword(intCat_Id) & "' ORDER BY MSG_LAST_POST DESC"
Then add a function
function fixword(stext)
fixword = replace(stext,"'","''")
end function
Maybeyour querystring is passing a ' and that can cause an error too.