ORA-14450: attempt to access a transactional temp table already in use

I need to alter the global temp. table but its not letting me alter it
and throwing the below error,i tried few times at regular interval but no use,is there a way to find out who is actually using it?

ERROR at line 1:
ORA-14450: attempt to access a transactional temp table already in use 

Cause :

           If the global temporary table was created with "on commit preserve rows" option,
the global temp table would still be locked eventhough transaction was commited.


Action :

           Disconnect and connect the session