unable to init duplicate delivery database

[Libor Kunes]

Hello,
I have Cent OS 3.4 and I have installed cyrus-imap 2.2. Everything ran 
OK. When I have started cyrus-imapd my maillog started to increase 
drastically with the following errors:
    lmtpunix: DBERROR: opening /var/imap/deliver.db: cyrusdb error
    lmtpunix[1515]: FATAL: lmtpd: unable to init duplicate delivery 
database
    unable to initialize inviromnent loc

All these errors keep going on and on. I remove the contents of the db 
folder and deliver.db and restarted cyrus-imapd. I did not help. These 
mistakes stopped occuring when I removed /var/lib/imap/socket folder but 
I was not able to receive any mail. I also tried to reinstal the whole 
cyrus-imap but in vain.

Could anyone help me what to do to repair this problem?
Thanks a lot

Libor