drop table if exists tempMix4 (no replies)

Hi,
from time to time on my log appear the following lines stucking the replicatione

110522 19:22:36 server id 2 log_pos 1297 Query thread_id=174211 exec_time=0 error_code=0
use mysql;
SET TIMESTAMP=1306084956;
drop table if exists tempMix4;
# at 1362
#110522 19:22:37 server id 2 log_pos 1362 Query thread_id=174211 exec_time=0 error_code=0
SET TIMESTAMP=1306084957;
create table if not exists tempMix4(data LONGBLOB);
# at 1448
#110522 19:22:55 server id 2 log_pos 1448 User_var
SET @`a`:=_binary 0x4D and a very long string

at this point the replication stucks

Can anyone help?
Thanks
Antonio