I get the same problem. I found '\0's in the messages that caused the hang and this fix works for me - whether it is the right thing I couldn't say.
John diff -ruN mutt-1.5.9.orig/imap/message.c mutt-1.5.9/imap/message.c --- mutt-1.5.9.orig/imap/message.c 2005-07-29 16:02:15.226860408 +0100 +++ mutt-1.5.9/imap/message.c 2005-07-29 16:01:13.446252488 +0100 @@ -590,6 +590,9 @@ for (last = EOF, len = 0; (c = fgetc(fp)) != EOF; last = c) { + if (c == '\0') + continue; + if (c == '\n' && last != '\r') buf[len++] = '\r'; -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]