I do not need a solution (just sharing information)
While we were trying to push install FSA Agent on a Windows 2003 R2 file server the installation was stuck, log shows following
Starting the log
30/10/2012 - 18:59:29 Initialising....
30/10/2012 - 18:59:29 Machine paramters: MachineName file01.domain.local, UserName domain\vsa, INIFileName EVPush.INI, InstallationLogFileName EVFSAInst.log, PushLogFilePath C:\ProgramData\Symantec\Enterprise Vault\PushLogs
30/10/2012 - 18:59:29 Reading INI file EVPush.INI
30/10/2012 - 18:59:29 Connecting...
30/10/2012 - 18:59:29 Creating thread to connect
30/10/2012 - 18:59:29 Inside ThreadToConnect. Initialising COM library
30/10/2012 - 18:59:29 Refer to the <Windows>\System32 or SysWOW64\bepushes.log for more information
30/10/2012 - 18:59:29 Inside ThreadToConnect. Creating object of class associated with CLSID_CEVPushWrapper
30/10/2012 - 18:59:29 Inside ThreadToConnect. Checking remote credentials. Server file01.domain.local, UserName domain\vsa, SourceDir d:\Program Files (x86)\Enterprise Vault\EVPush\VxPush
30/10/2012 - 18:59:37 Inside ThreadToConnect. Connected to remote machine. Got share \\file01.domain.local\BEW-b13e822fa8244e7eae95fb045ff280dc
30/10/2012 - 18:59:37 Connecting remote registry
30/10/2012 - 18:59:37 Getting Processor Identifier on remote machine
30/10/2012 - 18:59:37 Processor Identifier of remote machine: x86 Family 6 Model 26 Stepping 5, GenuineIntel
30/10/2012 - 18:59:37 Creating components
30/10/2012 - 18:59:37 Notification: RegOpenKeyEx returned error. Key: SOFTWARE\KVS\Enterprise Vault\Install, Value: PlaceHolder, Error code: 0x2
30/10/2012 - 18:59:37 Notification: RegOpenKeyEx returned error. Key: SOFTWARE\SYMANTEC\VXPUSH, Value: LogOptions, Error code: 0x2
30/10/2012 - 18:59:37 LogOptions value not found in SOFTWARE\SYMANTEC\VXPUSH, defaulting log options to /l*v
30/10/2012 - 18:59:37 Command line initialised: /i "C:\BEW-b13e822fa8244e7eae95fb045ff280dc\temp\ScSetup\Enterprise Vault File System Archiving.msi" /l*v EVFSAInst.log REBOOT=ReallySuppress
30/10/2012 - 18:59:37 Paramaters passed to CMachine c'tor: MachineName file01.domain.local, UserName domain\vsa, Password **********, INIFile EVPush.INI, InstallationLogFileName EVFSAInst.log, PushLogFilePath C:\ProgramData\Symantec\Enterprise Vault\PushLogs
30/10/2012 - 18:59:37 Loading FSAClusterConfiguration DLL d:\Program Files (x86)\Enterprise Vault\Utilities\FSA Cluster\FSACluster.dll
30/10/2012 - 18:59:37 Address of functions: SC_LoadApiLibrary 6CD0AB70, SC_VirtualServerNodesCollection 6CD0AF00, SC_VirtualServerNodesByIndex 6CD0B2C0 SC_ReleaseVirtualServerNodesCollection 6CD0B2E0
30/10/2012 - 18:59:37 Parameters passed to SC_VirtualServerNodesCollection: MachineName file01.domain.local, UserName vsa, Password **********, Domain DOMAIN
30/10/2012 - 18:59:38 SC_LoadApiLibrary Failed
30/10/2012 - 18:59:39 SC_VirtualServerNodesCollection returns numbers of nodes: 0
30/10/2012 - 18:59:39 Total nodes detected 0
30/10/2012 - 18:59:39 Notification: RegOpenKeyEx returned error. Key: SOFTWARE\SYMANTEC\VXPUSH, Value: status, Error code: 0x2
30/10/2012 - 18:59:39 Creating LST file
30/10/2012 - 18:59:39 Creating LST File. LST File path H:\Temp\7\
30/10/2012 - 18:59:39 Setting MSI properties into CMD line
30/10/2012 - 18:59:39 Creating Push Thread
30/10/2012 - 18:59:39 Creating Thread to read status
30/10/2012 - 18:59:39 Getting status of push thread copying files
30/10/2012 - 18:59:39 Notification: RegOpenKeyEx returned error. Key: SOFTWARE\SYMANTEC\VXPUSH, Value: status, Error code: 0x2
30/10/2012 - 18:59:40 ThreadToReadStatus: Waiting...
30/10/2012 - 18:59:40 ThreadToReadStatus: Waiting...
30/10/2012 - 18:59:41 ThreadToReadStatus: Waiting...
LOTS OF THESE ...............
30/10/2012 - 19: 0: 4 Notification: RegOpenKeyEx returned error. Key: SOFTWARE\SYMANTEC\VXPUSH, Value: status, Error code: 0x6
30/10/2012 - 19: 0: 4 Starting Thread to push
30/10/2012 - 19: 0: 4 Notification: RegOpenKeyEx returned error. Key: SOFTWARE\Microsoft\Windows NT\CurrentVersion, Value: CurrentVersion, Error code: 0x6
30/10/2012 - 19: 0: 4 Notification: RegCreateKeyEx returned error. Key: SOFTWARE\SYMANTEC\VXPUSH, Value: DATA4, Data: /i "C:\BEW-b13e822fa8244e7eae95fb045ff280dc\temp\ScSetup\Enterprise Vault File System Archiving.msi" /l*v EVFSAInst.log REBOOT=ReallySuppress FEATURE_PLACEHOLDER="1" ALLUSERS="2", Error code: 0x6
30/10/2012 - 19: 0: 4 Notification: RegCreateKeyEx returned error. Key: SOFTWARE\SYMANTEC\VXPUSH, Value: DATA3, Data: DOMAIN, Error code: 0x6
30/10/2012 - 19: 0: 4 Notification: RegCreateKeyEx returned error. Key: SOFTWARE\SYMANTEC\VXPUSH, Value: DATA1, Data: vsa, Error code: 0x6
30/10/2012 - 19: 0: 4 Error writing commandline and/or credentials to remote registry. Error code 0
30/10/2012 - 19: 0: 4 ThreadToPush: Error code 0x0
30/10/2012 - 19: 0: 4 ThreadToPush exit code, 1
30/10/2012 - 19: 0: 4 Installation files pushed successfully. Starting installation.
30/10/2012 - 19: 0: 6 Starting thread to read status from key SOFTWARE\SYMANTEC\VXPUSH on remote server
30/10/2012 - 19: 0: 6 Notification: RegOpenKeyEx returned error. Key: SOFTWARE\SYMANTEC\VXPUSH, Value: status, Error code: 0x6
30/10/2012 - 19: 0: 6 Notification: RegOpenKeyEx returned error. Key: SOFTWARE\SYMANTEC\VXPUSH, Value: status, Error code: 0x6
30/10/2012 - 19: 0: 7 Notification: RegOpenKeyEx returned error. Key: SOFTWARE\SYMANTEC\VXPUSH, Value: status, Error code: 0x6
30/10/2012 - 19: 0: 8 Notification: RegOpenKeyEx returned error. Key: SOFTWARE\SYMANTEC\VXPUSH, Value: status, Error code: 0x6
LOTSS OF THESE ...............
Finally we just clicked the 'X' button to close the install wizard and retried installation from another EV FSA Server and installation went fine.