[Dovecot] Problem: "Missing IMAP reply key: F"

Hi all:

I installed dovecot v1.0 (on Mac OS X) and want to connect to is on localhost via Pine or Alpine, but it fails. Pine's debug mode tells me the following:

Debug output of the Pine program (debug=2 debug_imap=4). Version 4.64 (OSX)
[...]
Terminal type: screen
About to open folder "INBOX"    inbox is: "INBOX"
IMAP 14:40:22 1/11 mm_log babble: Trying IP address [::1]
IMAP 14:40:22 1/11 mm_log warning: Connection failed to localhost,143: Connection refused
IMAP 14:40:22 1/11 mm_log babble: Trying IP address [127.0.0.1]
IMAP DEBUG 14:40:22 1/11: F
IMAP 14:40:22 1/11 mm_notify warning: {localhost}inbox: Missing IMAP reply key: F
IMAP 14:40:22 1/11 mm_notify bye: {localhost}inbox: [CLOSED] IMAP connection broken (server response)
IMAP 14:40:22 1/11 mm_log error: [CLOSED] IMAP connection broken (server response)

I use the options "disable_plaintext_auth = no" and "ssl_disable = yes", because I don't need encryption. (I only access the server from localhost.)

What does "Missing IMAP reply key: F" mean? Any easy way to solve the problem?

Thanks for any hint! Claus