Problem with Bayes learning

[Jonathan Nie]

Greetings!

I got a problem when I try to feed Bayes with large number of emails 
(over 1500). It just hang there and I got the the following error 
messages from maillog file:

.....bayes: cannot open bayes databases /spamassassin/bayes_* R/W: lock 
failed: File exists

Does anyone know how to fix it?

Thanks.

Jonathan