Pointing back to an earlier post by Sandra G., it sounds like all of the troubleshooting has been done in non-console RDP sessions? I did not see it mentioned, but did the initial installation and/or subsequent SEPM installs/repairs also take place via RDP? If this is the case, my first suggestion would be to either use the /console switch to gain at least a shadow (TCP#0) session, or use the previously mentioned solutions to gain console access.
Verify which session you're in if you attempt to use the console switch as the default domain policy does not allow RDP console connection. Use the 'set' command from a command prompt and verify the 'SESSIONNAME' equals 'console' or TCP#0.
After gaining console access, we need to start at square one - I know, again?! Uninstall LU, delete C:\Documents and Settings\All Users\Application Data\Symantec\LiveUpdate Liveupdate folder, reinstall LU, then uninstall/reinstall SEPM. From the log.liveupdate:
3/30/2010, 21:34:27 GMT -> Evaluating the following PreCondition for Product: SESM Content Catalog, Version: 11.0, Language: SymAllLanguages, ItemSeqName: HOTFIX
bSelect=(RegKeyExists("HKLM", "SOFTWARE\\Symantec\\Symantec Endpoint Protection\\SEPM") &&
(CompareFileVersions(GetRegValue ("HKLM", "SOFTWARE\\Symantec\\Symantec Endpoint Protection\\SEPM", "Version"), "11.0.5017.306") <= 0 ) &&
(GetRegValue ("HKLM", "SOFTWARE\\Symantec\\Symantec Endpoint Protection\\SEPM", "AllowSoftwareLiveUpdate")=="<NULL>" ||
(GetRegValue ("HKLM", "SOFTWARE\\Symantec\\Symantec Endpoint Protection\\SEPM", "AllowSoftwareLiveUpdate") != "0") ) &&
(GetPartialFileHash( AppendPath( GetRegValue ("HKLM", "SOFTWARE\\Symantec\\Symantec Endpoint Protection\\SEPM", "TargetDir"), "tomcat\\webapps\\scm\\WEB-INF\\lib\\scm-server.jar"), 10240 )=="0BE4C8E95F1BF1715E8041DED3BDC3C1593B0CDD"));
3/30/2010, 21:34:27 GMT -> Calling RegKeyExists ().
3/30/2010, 21:34:27 GMT -> The regkey "SOFTWARE\Symantec\Symantec Endpoint Protection\SEPM" in "HKLM" exists = true.
3/30/2010, 21:34:27 GMT -> Calling GetRegValue ().
3/30/2010, 21:34:27 GMT -> The registry value "Version" in "SOFTWARE\Symantec\Symantec Endpoint Protection\SEPM" at "HKLM" was "11.0.5002.333".
3/30/2010, 21:34:27 GMT -> Calling CompareFileVersions ()
3/30/2010, 21:34:27 GMT -> Comparing version string 11.0.5002.333 to 11.0.5017.306.
3/30/2010, 21:34:27 GMT -> CompareFileVersions returned -1
3/30/2010, 21:34:27 GMT -> -1 <= 0 evaluated to true.
3/30/2010, 21:34:27 GMT -> true && true evaluated to true.
3/30/2010, 21:34:27 GMT -> Calling GetRegValue ().
3/30/2010, 21:34:27 GMT -> The registry value "AllowSoftwareLiveUpdate" in "SOFTWARE\Symantec\Symantec Endpoint Protection\SEPM" at "HKLM" could not be found, defaulting to "<NULL>".
3/30/2010, 21:34:27 GMT -> "<NULL>" == "<NULL>" evaluated to true.
3/30/2010, 21:34:27 GMT -> Calling GetRegValue ().
3/30/2010, 21:34:27 GMT -> The registry value "AllowSoftwareLiveUpdate" in "SOFTWARE\Symantec\Symantec Endpoint Protection\SEPM" at "HKLM" could not be found, defaulting to "<NULL>".
3/30/2010, 21:34:27 GMT -> "<NULL>" != "0" evaluated to true.
3/30/2010, 21:34:27 GMT -> true || true evaluated to true.
3/30/2010, 21:34:27 GMT -> true && true evaluated to true.
3/30/2010, 21:34:27 GMT -> Calling GetRegValue ().
3/30/2010, 21:34:27 GMT -> The registry value "TargetDir" in "SOFTWARE\Symantec\Symantec Endpoint Protection\SEPM" at "HKLM" was "C:\Program Files (x86)\Symantec\Symantec Endpoint Protection Manager\".
3/30/2010, 21:34:27 GMT -> Calling AppendPath ().
3/30/2010, 21:34:27 GMT -> AppendPath combined "C:\Program Files (x86)\Symantec\Symantec Endpoint Protection Manager\" and "tomcat\webapps\scm\WEB-INF\lib\scm-server.jar" into "C:\Program Files (x86)\Symantec\Symantec Endpoint Protection Manager\tomcat\webapps\scm\WEB-INF\lib\scm-server.jar".
3/30/2010, 21:34:27 GMT -> Calling GetPartialFileHash ()
3/30/2010, 21:34:27 GMT -> The hash of "C:\Program Files (x86)\Symantec\Symantec Endpoint Protection Manager\tomcat\webapps\scm\WEB-INF\lib\scm-server.jar" is AD1DE665F18DD591138B9B68F5FA144B5A38D27C.
3/30/2010, 21:34:27 GMT -> "AD1DE665F18DD591138B9B68F5FA144B5A38D27C" == "0BE4C8E95F1BF1715E8041DED3BDC3C1593B0CDD" evaluated to false.
3/30/2010, 21:34:27 GMT -> true && false evaluated to false.
3/30/2010, 21:34:27 GMT -> bSelect was set to false.
3/30/2010, 21:34:27 GMT -> PreCondition evaluated to false, update will not be retrieved.
Further down:
3/30/2010, 21:35:02 GMT -> HR 0x802A0006 DECODE: E_DIS_SCRIPT_SYNTAX_ERROR
3/30/2010, 21:35:02 GMT -> EVENT - PRODUCT UPDATE FAILED EVENT - Update available for Antivirus and antispyware definitions Win32 11.0 MicroDefsB.CurDefs - MicroDefsB.CurDefs - SymAllLanguages. Update for CurDefs takes product from update 0 to 100330009. Server name - liveupdate.symantecliveupdate.com, Update file - 1269969298jtun_nav2k8enncur25.m25, Signer - cn=Symantec Corporation,ou=Usage - Prod02SigningToken,ou=Locality - Arizona,ou=Product Group - LiveUpdate,ou=SymSignature,o=Symantec Corporation, package install code 0. The Update executed with a result code of 1825, => The install script for this product had a syntax error, so LiveUpdate could not install it.
It appears the calendar dating patch did not apply correctly, causing the script syntax error, resulting in LU not being able to process the downloaded content. After reinstalling SEPM, allow the SEPM to perform LU to cycle through the patch sequence - typically 24 hours is needed for all 4 patches to be applied.