Windows XP Clients, fully patched, with Symantec Endpoint Protection 11 client

Windows 2008 R2 domain Roaming profiles Folder Redirection applied to Documents, AppData & Desktop

I've enabled userenv logging, and logged on just after 17:00 last night. The user shell hadn't appeared at 17:45 when I left last night. When I arrived this morning, I checked the log file and found the following.

USERENV(3f8.e7c) 17:02:18:296 LogExtSessionStatus: Successfully logged Extension Session data
USERENV(654.a30) 17:04:09:468 ImpersonateUser: Failed to impersonate user with 5.
USERENV(654.a30) 17:04:09:468 GetUserNameAndDomain Failed to impersonate user
USERENV(654.a30) 17:04:09:468 GetUserDNSDomainName:  Domain name is NT Authority.  No DNS domain name available.
USERENV(c8c.cb8) 17:04:09:781 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(cd0.cd4) 17:04:10:781 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(d08.c84) 17:07:09:609 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(cbc.cc0) 17:07:10:625 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\luall.exe
USERENV(db0.db4) 17:07:10:781 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(e00.e0c) 17:07:11:062 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\LuCallbackProxy.exe
USERENV(e20.e34) 17:07:11:203 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\LuCallbackProxy.exe
USERENV(e40.e50) 17:07:11:406 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\LuCallbackProxy.exe
USERENV(efc.54c) 17:07:11:656 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\LuCallbackProxy.exe
USERENV(ccc.df0) 17:08:45:687 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(e24.e20) 17:08:45:937 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\luall.exe
USERENV(ff0.ff4) 17:08:46:078 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(32c.cd0) 17:08:46:265 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\LuCallbackProxy.exe
USERENV(cc4.3d4) 17:08:46:406 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\LuCallbackProxy.exe
USERENV(434.4d0) 17:08:46:593 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\LuCallbackProxy.exe
USERENV(f2c.ac) 17:08:46:828 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\LuCallbackProxy.exe
USERENV(d60.d7c) 17:09:40:265 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(d94.d98) 17:09:40:531 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(bc4.3c4) 17:10:52:765 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(37c.90c) 17:10:52:984 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\luall.exe
USERENV(580.540) 17:10:53:109 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(c18.c30) 17:10:53:312 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\LuCallbackProxy.exe
USERENV(c44.288) 17:10:53:468 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\LuCallbackProxy.exe
USERENV(a34.cf4) 17:10:53:656 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\LuCallbackProxy.exe
USERENV(d3c.d4c) 17:10:53:890 LibMain: Process Name:  C:\Program Files\Symantec\LiveUpdate\LuCallbackProxy.exe
USERENV(970.948) 17:15:09:468 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(150.9dc) 17:15:09:734 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(f90.cec) 17:20:38:718 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(d8c.d70) 17:20:38:984 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(9a0.fa0) 17:26:07:953 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(844.51c) 17:26:08:218 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(d00.9ac) 17:31:19:453 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(ad4.624) 17:31:19:718 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(654.694) 17:31:46:390 ImpersonateUser: Failed to impersonate user with 5.
USERENV(654.694) 17:31:46:390 GetUserNameAndDomain Failed to impersonate user
USERENV(654.694) 17:31:46:390 GetUserDNSDomainName:  Domain name is NT Authority.  No DNS domain name available.
USERENV(af8.610) 17:36:48:625 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(aa4.dfc) 17:36:48:906 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(2dc.5c8) 17:42:17:812 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(f70.8ac) 17:42:18:078 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(d50.c30) 17:47:47:062 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(c2c.c3c) 17:47:47:328 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(ef0.4cc) 17:53:16:234 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(cd4.c84) 17:53:16:500 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE
USERENV(828.8c4) 17:58:45:484 LibMain: Process Name:  C:\Program Files\Symantec\Symantec Endpoint Protection\SescLU.exe
USERENV(a24.b30) 17:58:45:750 LibMain: Process Name:  C:\PROGRA~1\Symantec\LIVEUP~1\LUCOMS~1.EXE

I've seen posts suggesting that it may be Windows Desktop Search 3.01 that is causing this, so I've removed that.

I've removed the policy, 'Always wait for the network at startup or logon', thinking that might have helped.

I'm running out of ideas. Has anyone seen this before?