Set of SQL statements are slow/hung -- Going into endless loop with wait event : latch: cache buffer

DB Version:11.2.0.3

Platform : Red Hat Enterprise Linux Server release 5.8 (Tikanga)

A particular set of SQL statements are slow/hung in the database. These statements differentiates from each other in terms of number of columns selection from front end by the customer and the values of the bind variables.

Below is the one of the example of the SQL statement which is not returning data back to application..

SQL Text  : SELECT

          T21.CONFLICT_ID,

          T21.LAST_UPD,

          T21.CREATED,

          T21.LAST_UPD_BY,

          T21.CREATED_BY,

          T21.MODIFICATION_NUM,

          T21.ROW_ID,

          T21.LAST_UPD,

          T21.DOCNUM_GNRTD_FLG,

          T21.X_NEW_SUBMIT_DT,