Airport Interference

[John M. Hughes]

I have a Ti 400  running 10.3 with an airport card and an airport 
extreme base. I live in a large apartment building and normally have 
good reception except that every night about 10:00 PM my signal dies 
for 30 minutes to an hour.  When I check the menu bar I see that there 
is another signal coming in although it is too weak to log onto.  Is 
there anything I can do to block the other signal(s)? Do you think this 
is causing my problem?