Fix "Got error 134 from storage engine"

Hi, I have a table "pc_table" not working well. One of the errors is "Got error 134 from storage engine". I would appreciate if someone could help.

mysql> select * from pc_table where pc_id=654565;
ERROR 1030 (HY000): Got error 134 from storage engine

also when i do a "insert into pc_table blabla" I will get the following error:
"DBD::mysql::st execute failed: Duplicate entry '654565' for key 1"

My php script was not able to connect to the database today and I had to restart mysqld. I think probably this "error 134" error is the reason?

And here is the output from "check table":

mmysql> check table pc_table EXTENDED;
+----------------------+-------+----------+--------------------------------------------------------------------------------------------+
| Table                | Op    | Msg_type | Msg_text                                                                                   |
+----------------------+-------+----------+--------------------------------------------------------------------------------------------+
| mydb.pc_table | check | warning  | Table is marked as crashed                                                                 |
| mydb.pc_table | check | warning  | 2 clients are using or haven't closed the table properly                                   |
| mydb.pc_table | check | error    | Invalid key block position: 284932588628148224  key block size: 1024  file_length: 3870720 |
| mydb.pc_table | check | error    | key delete-link-chain corrupted                                                            |
| mydb.pc_table | check | error    | Corrupt                                                                                    |
+----------------------+-------+----------+--------------------------------------------------------------------------------------------+

Could somebody tell me:
1) what's the cause of the error? and how to prevent it in the future?
2) what's the best way to fix it? Use 'repair table' or load the corrupted pc_table from a backup? (I have a 1 day old backup).
Lose a few records is ok for me but I need to make sure this doesn't affect other tables in the database and the same problem doesn't happen again.

Thank you very much.