cyrus imapd segfaults

[bsh]

after upgrading from ubuntu 8.04 to 10.04 directly, my cyrus server stopped working. (among many other things...)
after fixing the db type issues, it still won't work. now at least it starts up, but crashes as soon as something tries to connect to it. (a client, or a cyrus tool, like cyradm.)

snippet from imap.log:

May 12 22:45:51 localhost cyrus/master[1127]: process started
May 12 22:45:52 localhost cyrus/master[1184]: about to exec /usr/sbin/ctl_cyrusdb
May 12 22:45:54 localhost cyrus/ctl_cyrusdb[1184]: recovering cyrus databases
May 12 22:45:54 localhost cyrus/ctl_cyrusdb[1184]: skiplist: recovered /var/lib/cyrus/mailboxes.db (50 records, 5180 bytes) in 0 seconds
May 12 22:45:54 localhost cyrus/ctl_cyrusdb[1184]: skiplist: recovered /var/lib/cyrus/annotations.db (0 records, 144 bytes) in 0 seconds
May 12 22:45:54 localhost cyrus/master[1127]: process 1184 exited, signaled to death by 7
May 12 22:45:54 localhost cyrus/master[1364]: about to exec /usr/sbin/cyr_expire
May 12 22:45:54 localhost cyrus/cyr_expire[1364]: duplicate_prune: pruning back 3 days
May 12 22:45:54 localhost cyrus/cyr_expire[1364]: duplicate_prune: purged 0 out of 0 entries
May 12 22:45:54 localhost cyrus/cyr_expire[1364]: expunged 0 out of 0 messages from 0 mailboxes
May 12 22:45:54 localhost cyrus/master[1365]: about to exec /usr/sbin/tls_prune
May 12 22:45:54 localhost cyrus/tls_prune[1365]: tls_prune: purged 0 out of 1 entries
May 12 22:45:54 localhost cyrus/master[1127]: ready for work
May 12 22:45:54 localhost cyrus/master[1366]: about to exec /usr/sbin/ctl_cyrusdb
May 12 22:45:54 localhost cyrus/master[1367]: about to exec /usr/lib/cyrus/bin/notifyd
May 12 22:45:54 localhost cyrus/ctl_cyrusdb[1366]: checkpointing cyrus databases
May 12 22:45:55 localhost cyrus/notify[1367]: executed
May 12 22:45:55 localhost cyrus/ctl_cyrusdb[1366]: archiving database file: /var/lib/cyrus/annotations.db
May 12 22:45:55 localhost cyrus/ctl_cyrusdb[1366]: archiving log file: /var/lib/cyrus/db/log.0000000001
May 12 22:45:55 localhost cyrus/ctl_cyrusdb[1366]: archiving database file: /var/lib/cyrus/mailboxes.db
May 12 22:45:55 localhost cyrus/ctl_cyrusdb[1366]: archiving log file: /var/lib/cyrus/db/log.0000000001
May 12 22:45:56 localhost cyrus/ctl_cyrusdb[1366]: archiving log file: /var/lib/cyrus/db/log.0000000001
May 12 22:45:56 localhost cyrus/ctl_cyrusdb[1366]: done checkpointing cyrus databases
May 12 22:45:56 localhost cyrus/master[1127]: process 1366 exited, status 0
May 12 22:59:17 localhost cyrus/master[27178]: about to exec /usr/lib/cyrus/bin/imapd
May 12 22:59:17 localhost cyrus/imap[27178]: executed
May 12 22:59:17 localhost cyrus/imap[27178]: accepted connection
May 12 22:59:17 localhost cyrus/imap[27178]: login: phenom [192.168.2.60] bsh CRAM-MD5 User logged in
May 12 22:59:17 localhost cyrus/master[1127]: process 27178 exited, signaled to death by 7
May 12 22:59:17 localhost cyrus/master[1127]: service imap pid 27178 in BUSY state: terminated abnormally
May 12 22:59:17 localhost cyrus/master[27179]: about to exec /usr/lib/cyrus/bin/imapd
May 12 22:59:17 localhost cyrus/imap[27179]: executed
May 12 22:59:17 localhost cyrus/imap[27179]: accepted connection
May 12 22:59:17 localhost cyrus/imap[27179]: login: phenom [192.168.2.60] bsh CRAM-MD5 User logged in
May 12 22:59:17 localhost cyrus/master[1127]: process 27179 exited, signaled to death by 11
May 12 22:59:17 localhost cyrus/master[1127]: service imap pid 27179 in BUSY state: terminated abnormally
May 12 22:59:17 localhost cyrus/master[27180]: about to exec /usr/lib/cyrus/bin/imapd
May 12 22:59:17 localhost cyrus/imap[27180]: executed
May 12 22:59:17 localhost cyrus/imap[27180]: accepted connection
May 12 22:59:17 localhost cyrus/imap[27180]: login: phenom [192.168.2.60] bsh CRAM-MD5 User logged in
May 12 22:59:17 localhost cyrus/master[1127]: process 27180 exited, signaled to death by 11
May 12 22:59:17 localhost cyrus/master[1127]: service imap pid 27180 in BUSY state: terminated abnormally
May 12 22:59:17 localhost cyrus/master[27181]: about to exec /usr/lib/cyrus/bin/imapd
May 12 22:59:17 localhost cyrus/imap[27181]: executed
May 12 22:59:17 localhost cyrus/imap[27181]: accepted connection
May 12 22:59:17 localhost cyrus/imap[27181]: login: phenom [192.168.2.60] bsh CRAM-MD5 User logged in
May 12 22:59:17 localhost cyrus/master[1127]: process 27181 exited, signaled to death by 11
May 12 22:59:17 localhost cyrus/master[1127]: service imap pid 27181 in BUSY state: terminated abnormally
May 12 22:59:17 localhost cyrus/master[27182]: about to exec /usr/lib/cyrus/bin/imapd
May 12 22:59:17 localhost cyrus/imap[27182]: executed
May 12 22:59:17 localhost cyrus/imap[27182]: accepted connection
May 12 22:59:17 localhost cyrus/imap[27182]: login: phenom [192.168.2.60] bsh CRAM-MD5 User logged in
May 12 22:59:17 localhost cyrus/master[1127]: process 27182 exited, signaled to death by 11
May 12 22:59:17 localhost cyrus/master[1127]: service imap pid 27182 in BUSY state: terminated abnormally
May 12 22:59:17 localhost cyrus/master[27183]: about to exec /usr/lib/cyrus/bin/imapd
May 12 22:59:17 localhost cyrus/imap[27183]: executed
May 12 22:59:17 localhost cyrus/imap[27183]: accepted connection
May 12 22:59:17 localhost cyrus/imap[27183]: login: phenom [192.168.2.60] bsh CRAM-MD5 User logged in
May 12 22:59:17 localhost cyrus/master[1127]: process 27183 exited, signaled to death by 11
May 12 22:59:17 localhost cyrus/master[1127]: service imap pid 27183 in BUSY state: terminated abnormally
May 12 22:59:17 localhost cyrus/master[27184]: about to exec /usr/lib/cyrus/bin/imapd
May 12 22:59:18 localhost cyrus/imap[27184]: executed
May 12 22:59:18 localhost cyrus/imap[27184]: accepted connection
May 12 22:59:18 localhost cyrus/imap[27184]: login: phenom [192.168.2.60] bsh CRAM-MD5 User logged in
May 12 22:59:18 localhost cyrus/master[1127]: process 27184 exited, signaled to death by 11
May 12 22:59:18 localhost cyrus/master[1127]: service imap pid 27184 in BUSY state: terminated abnormally
May 12 22:59:18 localhost cyrus/master[27185]: about to exec /usr/lib/cyrus/bin/imapd

at 22:59:17, the client starts to the server, which then keeps crashing and restarting.

another snippet from syslog:

May 12 22:59:17 localhost kernel: [ 826.945511] __ratelimit: 15 callbacks suppressed
May 12 22:59:17 localhost kernel: [ 826.945529] imapd[27179] general protection ip:6dcf7a sp:bfa3bbc8 error:0 in libc-2.11.1.so[5cd000+153000]
May 12 22:59:17 localhost kernel: [ 826.989351] imapd[27180] general protection ip:101ff7a sp:bffeb708 error:0 in libc-2.11.1.so[f10000+153000]
May 12 22:59:17 localhost kernel: [ 827.035577] imapd[27181] general protection ip:8daf7a sp:bfdc7fd8 error:0 in libc-2.11.1.so[7cb000+153000]
May 12 22:59:17 localhost kernel: [ 827.105168] imapd[27182] general protection ip:350f7a sp:bfc39618 error:0 in libc-2.11.1.so[241000+153000]
May 12 22:59:17 localhost kernel: [ 827.140784] imapd[27183] general protection ip:ed1f7a sp:bfffbed8 error:0 in libc-2.11.1.so[dc2000+153000]
May 12 22:59:18 localhost kernel: [ 827.188697] imapd[27184] general protection ip:835f7a sp:bfc45008 error:0 in libc-2.11.1.so[726000+153000]
May 12 22:59:18 localhost kernel: [ 827.223319] imapd[27185] general protection ip:720f7a sp:bfdb6a08 error:0 in libc-2.11.1.so[611000+153000]
May 12 22:59:18 localhost kernel: [ 827.249164] imapd[27186] general protection ip:38ef7a sp:bff36158 error:0 in libc-2.11.1.so[27f000+153000]
May 12 22:59:18 localhost kernel: [ 827.274923] imapd[27187] general protection ip:a8ff7a sp:bfff9218 error:0 in libc-2.11.1.so[980000+153000]
May 12 22:59:18 localhost kernel: [ 827.300192] imapd[27188] general protection ip:708f7a sp:bf8526c8 error:0 in libc-2.11.1.so[5f9000+153000]