Replication error (no replies)

Hi, after a whole system update on the slave system side, from Debian etch to Lenny, mysql replication is not working.

That's the error i get on slave side
mysql> start slave;
ERROR 1201 (HY000): Could not initialize master info structure; more error messages can be found in the MySQL error log

Loading data manually works fine:
mysql> load data from master;
Query OK, 0 rows affected, 2 warnings (1.97 sec)

Here's a bit of information (slave side):
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: ************
Master_User: ***
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000950
Read_Master_Log_Pos: 1771
Relay_Log_File: *******-relay-bin.000286
Relay_Log_Pos: 1908
Relay_Master_Log_File: mysql-bin.000950
Slave_IO_Running: No
Slave_SQL_Running: No
Replicate_Do_DB: ******
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 1771
Relay_Log_Space: 0
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: NULL

I think that's wrong
mysql> show master status\G;
*************************** 1. row ***************************
File: mysql-bin.000809
Position: 98
Binlog_Do_DB:
Binlog_Ignore_DB:

Executed on master side:
mysql> show master status\G;
*************************** 1. row ***************************
File: mysql-bin.000950
Position: 11252
Binlog_Do_DB:
Binlog_Ignore_DB:

Hope someone can help, thanks in advanced