name is already used

Team,

        I get
ORA-00955: name is already used by an existing object
When I try to recreate a table that has a blob in oracle 11.2.0.2.

Here the steps that are execute in  pl/sql code.

- drop table MY_TABLE CASCADE CONSTRAINTS PURGE;
- purge recyclebin
- create table MY_TABLE ..
Ex: ORA-00955: name is already used by an existing object

It does not happen all the time.

Any Help is really appreciated.

Hisham