Disappearing Sessions - Part 2

Oracle 10.2.0.3.0
Windows Server 2003
16 GB of memory

Our off-site DBA had this to say about the disappearing sessions and ORA-07445 errors:

 "I think the problem with disappearing sessions is the dispatcher process.

 when we increased the session limit, I did not take into account that there are web connections coming in also.

 ORA-07445 is defenitely points back to Hardware/OS. Since the memory upgrade (16 which will need to go to 32), we have not seen any errors."

Does this make sense when:

1. I'm running my process in Dedicated Server mode, not Shared Server.
2. If I add just one more nested table that gets loaded in my code my process will disappear however if I take it out my process will run to completion.
3. If I force a full table scan my process will complete. If I try using a FIRST_ROWS hint or change my query to use an extra column join (which seems to cause a hash join) my process disappears.

I should also state that just today, after receiving this information from our off-site DBA that the database went down (around the time it went down there looked like there was massive contention memory-wise) and we have a new ORA-07445 error. Received on Fri Feb 08 2008 - 16:07:15 CST