If you are in my NTEN217 class, this article is worth a read!
A student was having problems after customizing a packet tracer solution I had assigned to practice for the final exam. He stumbled across the issue of OSPF using fast timers (Hello & Dead timer) for point-to-point interfaces and slow timers point-to-multipoint Frame Relay interfaces. OSPF requires the Hello timers to be synchronized and so the adjacencies weren’t coming up. Anyway, the article explains it all so I won’t regurgitate it all.