Question on gc buffer busy waits

we are facing "gc buffer busy acquire waits" in our database intermittently. This is an OLTP system.
we are getting lot of blocking on our system. for example: 54 seconds in DB Time is spent waiting for TX lock

we are updating same table from all services that are on all nodes..this is our primary table..
the primary key on the table is auto-generated.

1. I updated all stats
2. re-indexed indexes..

Did anybody face the same problem???

will creating a reverse key index on primary solve our problem?? (table has abt 2 million records)

Thanks in advance..

--
http://www.freelists.org/webpage/oracle-l