Master-master replication: Working from B to A, but not from A to B (1 reply)

I'm having a big problem with a master-master replication I've set between two virtual machines that have MySQL 5.5.14 installed.

After the my.ini parameter additions and CHANGE MASTER TO, both servers show "Waiting for master to send event" in Slave_IO_State and "Yes" for both Slave_IO_Running and Slave_SQL_Running. Despite that, the replication only works from the second server to the first, but not from the first to the second.

Reinstalling MySQL solved the problem the first time I faced it, but now it's not working anymore.

Have you guys ever had a problem like this? Any ideas for solving it?

Thanks in advance.