We recently started to have this problem: after launching GW 8 and successfully signing in, for a few minutes everything is ok, but then a error pops up: Error 8912
The server or post office agent is no longer responding or has become disconnected. GroupWise will exit. If the problem persist, contact your system administrator
. Web client seems to work without any problems. Server reboot didn't do any good. Traffic load doesn't seem to be problematically heavy either.

Here is the postoffice.poa recent log head:

13:40:34 584 Successfully accessed Software Distribution Directory-/opt/novell/groupwise/software
13:40:34 584
13:40:34 584 ************************* Initializing ************************
13:40:34 496 Checking guardian database
13:40:34 616 Starting GWTCP-tmip-Handler_2
13:40:34 000 Starting GWTCP-tmip-Handler_1
13:40:34 384 Starting GWTCP-Dispatcher
13:40:34 768 Starting GWTCP-Listener
13:40:34 696 Starting GWTCP-tmip-Handler_7
13:40:34 080 Starting GWTCP-tmip-Handler_6
13:40:34 464 Starting GWTCP-tmip-Handler_5
13:40:34 848 Starting GWTCP-tmip-Handler_4
13:40:34 232 Starting GWTCP-tmip-Handler_3
13:40:34 312 Starting GWTCP-tmip-Handler_8
13:40:34 928 Starting GWTCP-tmip-Handler_9
13:40:34 544 Starting GWTCP-tmip-Handler_10
13:40:34 160 Starting GWTCP-Monitor
13:40:34 584 MTP: Starting Message Transfer Protocol Listener
13:40:34 584 MTP: Starting Message Transfer Protocol Scanner
13:40:34 584
13:40:34 584 Up Time: 0 Days 0 Hours 0 Minutes
13:40:34 584
13:40:34 584 General Settings:
13:40:34 584 Post Office Directory: /var/tmipostoffice/
13:40:34 584 Post Office Access Mode: Client/Server Only
13:40:34 584 Post Office Configuration Instance: POA
13:40:34 584 Post Office Language: en
13:40:34 584 Internet Domain Name: vtmt.lt
13:40:34 584 Read Configuration from Database: Yes
13:40:34 584 Error Mail to Administrator: Yes
13:40:34 584 Successfully accessed Software Distribution Directory: /opt/novell/groupwise/software
13:40:34 584 IPV6 Protocol: Enabled
13:40:34 584 QuickFinder Indexing: Enabled
13:40:34 584 QuickFinder Indexing Base Offset (hours from Midnight): 20 Hours 0 Mins (Default)
13:40:34 584 QuickFinder Indexing Interval: 24 Hours 0 Mins (Default)
13:40:34 584 Quarantine Files That Fail in Document Conversion: Disabled
13:40:34 584 Simple Network Management Protocol (SNMP): Disabled
13:40:34 584 Admin Task Processing: Yes
13:40:34 584 Intruder Detection: Enabled
13:40:34 584 Incorrect Login Attempts before Lockout: 5
13:40:34 584 Login Attempt Reset Interval: 30 mins
13:40:34 584 Intruder Lockout Reset Interval: 30 mins
13:40:34 584 GWCheck Processing: Enabled
13:40:34 584 Post Office Security Requires Password: Yes
13:40:34 584 LDAP Authentication: Disabled
13:40:34 584 Move User (live) via TCP/IP: Enabled
13:40:34 584
13:40:34 584 Internet Protocol Agent Settings:
13:40:34 584 IMAP Agent: Disabled
13:40:34 584 SOAP Agent: Disabled
13:40:34 584 Calendar/Free Busy Publishing: Disabled
13:40:34 584
13:40:34 584 Log Settings:
13:40:34 584 Log Level: Verbose
13:40:34 584 Disk Logging: Enabled
13:40:34 584 Log Directory: /var/log/novell/groupwise/tmipostoffice.poa
13:40:34 584 Maximum Log File Age: 30 Days (Default)
13:40:34 584 Maximum Log Disk Space: 102400 KB (Default)
13:40:34 584
13:40:34 584 Performance Settings:
13:40:34 584 Message Worker Threads: 6 (Default)
13:40:34 584 Maximum GWCheck Worker Threads: 4 (Default)
13:40:34 584 C/S Handler Threads: 10
13:40:34 584 Database Recovery: Enabled
13:40:34 584 Database Caching: Enabled
13:40:34 584 Nightly User Upkeep: Enabled
13:40:34 584 Nightly User Upkeep Offset (hours from midnight): 0 (Default)
13:40:34 584 Nightly Remote Downloadable Address Book Generation: Enabled
13:40:34 584 Nightly Rem AB Gen Offset (hours from midnight): 0 (Default)
13:40:34 584
13:40:34 584 Client/Server Settings:
13:40:34 584 Client/Server: Enabled
13:40:34 584 Client/Server over SSL: Disabled
13:40:34 584 IP Address: 192.168.100.58
13:40:34 584 eDirectory Object Name: POA.tmipostoffice.gwmail.tmi
13:40:34 584 TCP Port for C/S Connections: 1677 (Default)
13:40:34 584 Maximum Application Connections: 2048 (Default)
13:40:34 584 Maximum Physical Connections: 2048 (Default)
13:40:34 584 HTTP: Enabled
13:40:34 584 HTTP over SSL: Disabled
13:40:34 584 HTTP Port: 7181
13:40:34 584 HTTP Refresh rate: 60 secs
13:40:34 584 Enforce Lockout on Older GroupWise Clients: Disabled
13:40:34 584
13:40:34 584 Message Transfer Protocol:
13:40:34 584 Inbound MF traffic: 192.168.100.58, 7101
13:40:34 584 Outbound MF traffic: gwdom.vtmt.lt, 7100
13:40:34 776 Starting GWHTTP-tmip-Listener
13:40:34 584 Message Transfer over SSL: Disabled
13:40:34 584 MTP File Transfer Size Limit: 0 MB (No Limit)
13:40:34 584
13:40:34 584 Message File Processing Settings:
13:40:34 584 Directory Scanning for Message Files: Enabled
13:40:34 584 High Priority Directory Scanning: Enabled
13:40:34 584 Low Priority Directory Scanning: Enabled
13:40:34 584
13:40:34 584 Disk Check Events:
13:40:34 584 Disk Space Management: Enabled
13:40:34 584 Check Disk Space Every: 5 (mins)
13:40:34 584 Perform Disk Check Actions No More than Every: 2 (hrs)
13:40:34 584 Event #1 : Default Disk Check Event
13:40:34 584 Disk Space Threshold To Trigger Action: 2048MB
13:40:34 584 Disk Space Threshold To Stop Processing: 200MB
13:40:34 584 Action Set #1 : Default Disk Space Management Actions
13:40:34 584 Mail Message to Administrator: upon failure
13:40:34 584 Type of Database Files to Check: User Msg Doc
13:40:34 584 Database Check Action: Reduce
13:40:34 624 Starting GWHTTP-tmip-Handler_1
13:40:34 584 Distribute Database Check Log to Administrator
13:40:34 584 Delete Temporary/Backup Files Older than (days): 1
13:40:34 584
13:40:34 584 Database Maintenance Events:
13:40:34 584 Event #1 : Default Daily Maintenance Event
13:40:34 584 Days to Perform Action(s): Su M T W Th F Sa
13:40:34 584 Time to Perform Action(s): 2:00am
13:40:34 584 Action Set #1 : Default Mailbox/Library Structure Check
13:40:34 584 Type of Database Files to Check: User Msg Doc
13:40:34 584 Database Check Action: Analyze/Fixup
13:40:34 584 Level of Database Analysis and Verification: Structural
13:40:34 584 Distribute Database Check Log to Administrator
13:40:34 584 Delete Temporary/Backup Files Older than (days): 7
13:40:34 584 Event #2 : Default Weekly Maintenance Event
13:40:34 584 Days to Perform Action(s): Sa
13:40:34 584 Time to Perform Action(s): 3:00am
13:40:34 584 Action Set #1 : Default Mailbox/Library Content Check
13:40:34 584 Type of Database Files to Check: User Msg Doc
13:40:34 584 Database Check Action: Analyze/Fixup
13:40:34 584 Level of Database Analysis and Verification: Contents
13:40:34 584 Generate Database Check Statistics
13:40:34 584 Distribute Database Check Log to Administrator
13:40:34 584 Delete Temporary/Backup Files Older than (days): 7
13:40:34 584 Action Set #2 : Default Audit Report
13:40:34 584 Database Check Action:Unknown