Rollback causing excessive waits in cache buffers chains latch

In the past 6 months we have noticed random cases where processes that take 5-15 minutes to complete wait excessively on cache buffers chains latch. The process will eventually complete but can take anywhere from 10-40 hours to complete. Some pertinent points:

1. We are running 9.2.0.8 since it was released.
2. We have only noticed this issue in the last 6 months. The system has been operational for 10 years.
3. It only happens when the process is rolling back.
4. It has happend with only one logged in user in the system.
5. When it is occurring if I get all other users out of the system the wait still occurs. Latch contention is not reduced.