...did you revert to an earlier set of installation files?
The version of Liveupdate in teh latest log is 3.3.1.19, whereas is should be 3.3.1.23 with SEP12.1RTM and SEP12.1RU1 (SEP12.1RU1MP1 uses v3.3.2.2).
Also, this latest log has loads of entries similar to those below:
5/2/2012, 14:43:41 GMT -> ProductRegCom/luProductReg(PID=7896/TID=3012): Registering Product -- SEPM Virus Definitions Win32 v12.1 (Pre-Release) - Hub - SymAllLanguages
5/2/2012, 14:43:41 GMT -> ProductRegCom/luGroup(PID=7896/TID=3012): Adding product to Group {298349E5-0AB4-F6D4-01DD-B0AF43C58285} - Product = SEPM Virus Definitions Win32 v12.1 (Pre-Release), Version = Hub, Language = SymAllLanguages, Type =
These suggest LU is looking for definitions for the Pre-Release version of SEP? Can you confirm your SEPM version please?