Deadlock exception

[António Santos]

Hi there,

I've been using mysql++ 3.0 lately in a multithreaded program and  
sometimes, when I issue an INSERT query, I get an exception:
Deadlock found when trying to get lock; try restarting transaction
This happened when I was using transactions but then I removed the use  
of transactions and I get the same result.
Do anyone know why this is happening? I have a mutex that assures that  
two threads do not affect the same rows at the same time.

Thanks!

Antonio Santos
Portugal