OSPF just craps out after about one hour

I really need OSPF to work, and its giving me a very hard time.

I just have a simple backbone network installed of 0.0.0.0/0 for 2 routers, and it comes up fine, all the routes exchange with each router, but it only lasts for about an hour? one of the routers just drops all the routes in the routing table, even though they are both indicated as being neighbors still, and in the OSPF routing tables all the routes are still present.
ROS 3.3 on both, one is RB333, other is x86.

Nothing in the logs.

Anyone seen this?