Oracle 10g Database Locking Session Issue

I have a problem with locking and not timing out in one of my Oracle databases. This session locks occur on certain transactions that come from Oracle Forms users. For instance, when some user requests to make a change on a locked object the transaction waits for the locked object to be released, but it waits indefinetely until killed by alter session. I've tried the same in my testing database and it does kill the locked session after 60s, so I thought it has to be a configuration issue. I've checked the v$parameters DISTRIBUTED_LOCK_TIMEOUT and it is set to 60s in both databases. Does anyone know where is the "locking session/transaction timeout" set? Any help is greatly appreciated.