OSX Server and AFP "No matching key:"

After a restart of the server, no users could log in. They got authenticated, but then after a loooong delay their Finder said 'disconnected'.

Checking the AFP log on the server I see lots and lots of

IP 192.168.1.21 - - [21/Jun/2009:18:50:00 0000] "Login bob" 0 0 0
**** - - [21/Jun/2009:18:50:02 0000] "Mounted Volume XServer" 0 0 0
**** - - [21/Jun/2009:18:50:02 0000] "Mounted Volume Data" 1 0 0
**** - - [21/Jun/2009:18:50:02 0000] "Mounted Volume Disk1" 2 0 0
**** - - [21/Jun/2009:18:50:02 0000] "DiskArbStart -" 0 6403 0
IP 192.168.1.21 - - [21/Jun/2009:18:50:11 0000] "Login bob" 0 0 0
IP 192.168.1.21 - - [21/Jun/2009:18:50:11 0000] "Login bob" 0 0 0
IP 192.168.1.21 - - [21/Jun/2009:18:50:11 0000] "No matching key: bob" 1247645341 1243892782 92
**** - - [21/Jun/2009:18:50:12 0000] "Mounted Volume XServer" 0 0 0
**** - - [21/Jun/2009:18:50:12 0000] "Mounted Volume Disk2" 1 0 0
**** - - [21/Jun/2009:18:50:12 0000] "Mounted Volume Disk1" 2 0 0
**** - - [21/Jun/2009:18:50:12 0000] "DiskArbStart -" 0 6403 0
IP 192.168.1.21 - - [21/Jun/2009:18:50:21 0000] "Login bob" 0 0 0
IP 192.168.1.21 - - [21/Jun/2009:18:50:21 0000] "Login bob" 0 0 0
IP 192.168.1.21 - - [21/Jun/2009:18:50:21 0000] "No matching key: bob" 1247645341 1243892782 92

A restart didn't fix it, so decided to re-install the latest patch from the combo, in this case 10.4.11. Now everything is back to normal.