I've spent a bit of time trying to reproduce the error on the partition scheme, but cannot get the exact error with the orphaned table 

> 120927 16:57:04 [ERROR] Cannot find or open table reportingdb/v3_zone_date_cpm7k#P#pcurrent_2012926 from
the internal data dictionary of InnoDB though the .frm file for the
table exists.

By moving the .ibd file for the partition out of the data directory (which it seems somehow has happened), I get an expected error:

> [ERROR] MySQL is trying to open a table handle but the .ibd file for
table foo/v3_zone_date_cpm7k#P#pcurrent_2012822 does not exist.

From a chat discussion I know you have an outdated backup file. Barring actually being able to force drop the partition 'pcurrent_2012926' (some data loss), the steps to restore this backup are as follows (a month worth of data loss unfortunately):

- Take a backup of your main server (just in case!)
- Restore the backup on a different server
- Take a mysqldump of the table: `mysqldump -uuser -p reportingdb v3_zone_date_cpm7k > v3_zone_date_cpm7k.sql`
- copy v3_zone_date_cpm7k.sql to the main server
- On the main server, attempt to do this: `DROP TABLE reportingdb.v3_zone_date_cpm7k`
- If that works, import your dumpfile: `mysql -uuser -p reportingdb < v3_zone_date_cpm7k.sql` which should restore that table (with a month-old table)
- If the `DROP TABLE` does not work, try moving the `v3_zone_date_cpm7k.frm` and other files to a different location and restarting the server. And reissue the `DROP TABLE` command. 

The last step is in regards to the error message telling you you have an orphaned table:

>This means that there is an orphaned .frm file without a corresponding table inside InnoDB. You can drop the orphaned .frm file by deleting it manually. [\[src\]][1]

I really hope this is not necessary and you can restore the partition by another means. This is a last resort method.


  [1]: http://dev.mysql.com/doc/refman/5.5/en/innodb-troubleshooting-datadict.html