[Dovecot] Seen this behavior before?

Hi,

it's not yet a bug report, just a question:

After I was successfully using dovecot-imap and Thunderbird for quite a while without any problem (debian unstable), I now sometimes experience that the IMAP-connection hangs and thunderbird waits forever when accessing a folder. I did not yet analyze the problem and I am not sure whether it is a thunderbird or a dovecot problem.

Did anyone see this behavior before?

regards Hadmut