Your SGA has become fragmented ...
Your will have to restart the database to clear up the fragmentation.

Your should attempt to pin some of the objects in memory that
are getting reloaded multiple times... See script below to view
the reloads and sizes of objects...

You also may need to look at resizing your SGA

Another aid is the following undocumented init parameter in 8.1.7

#### Work around for BAMIMA Buffer (4031) errors ####
_db_handles_cached = 0


To determine what large PL/SQL objects are currently loaded in the shared pool
and are not marked 'kept' and therefore may cause a problem, execute the following:


select substr(owner,1,10),substr(name,1,32), sharable_mem,loads,executions
from v$db_object_cache
where sharable_mem > 100
and (type = 'PACKAGE' or type = 'PACKAGE BODY' or type = 'FUNCTION'
or type = 'PROCEDURE')
and kept = 'NO'
order by owner,loads desc;


--- Objects that have been reloaded ---

select substr(owner,1,10),substr(name,1,32), sharable_mem,loads,executions
from v$db_object_cache
where loads > 1
and (type = 'PACKAGE' or type = 'PACKAGE BODY' or type = 'FUNCTION'
or type = 'PROCEDURE')
and kept = 'NO'
order by owner,loads desc;

Hope this helps
Gregg