Pls check in task manger any process is running related to liveupate(luall.exe,callbackproxy.exe ,lucom.exe) ,if anything present kill that process and try to uninstall.. 

Hi Aravind...

We are unable to stop those processes...Its giving access denied error......I tried removing it by running the setup file (which will give repair..remove and modify options).....After the half way...its hanging......But in services.msc....no services related to SEP are running....Is there any other tool to remove SEP other than cleanwipe....

Once you restart your pc and try to uninstall 

How to manually uninstall Symantec Endpoint Protection client from Windows 2000, XP and 2003, 32-bit Editions 

The user which you are using for uninstalling is an admin user ,I am correct?
One more thig why you are uninstalling SEP from that pc? 

seems like autoprotect is protecting liveupdate.
open cmd prompt
type taskkill /f /im "luall.exe"
or
disable tamper protection

Enabling, disabling, and configuring Tamper Protection in Endpoint Protection on unmanaged Clients
http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007101809460948?Open&seg=ent

once you kill LU you will be able to uninstall

The running services mentioned by you are interdependent therefore its possible that you might get a access denied error eeven if you are logged in as an Administrator. You can manually remove the SEP installatio although the process is lengthy it ensures a complete removal of the Symantec endpoint.

http://service1.symantec.com/SUPPORT/ent-security....

 Reboot your machine and then kill the Lu* processes if still its not working install Unlocker  and kill these processes using it.
then delete the folder \program files\symantec\liveupdate then try installing SEP again.

 Ok..for the first part of your issue is resolved now its the second part right ( un-install complete but unable to re-install0
Delete
C:\Documents and Settings\All Users\Application Data\Symantec
C:\Program Files\Symantec
C:\Program Files\Symantec Endpoint Protection or
C:\Program Files\Symantec Antivirus,

C:\Program Files\Common Files\Symantec Shared.

Clear out start - run - %temp%

reboot the computer once

Then run the install again.
If Sucess then good if not then go to
%temp%\SEP_INST.log

Look for 1st Return Value 3
And paste 10 line above this value over here we'll go from there..

Hi Vikram,

Am not clear on how to perform the last two step....pasting 10 line above this value....can u plss explain...

 SEP installation creates a install log which is located in start - run - %temp%  ( temp folder for the user profile)
SEP_INST.log

it will be a huge log file. Open it notepad ( by default it will open in notepad)
in the log search for Return value 3  
(Return value 3 is generated when install fails it shows the reason why install failed)

then copy 10-15 line above this return value 3 and paste it on this forum so that we can determine what is causing the install failure and can recommend you further steps to perform.

Open the file %temp%\SEP_INST.log
Search for the value  Return Value 3
You may get multiple times this same error
Look at the first time value paste 10 lines above it

Hi......

Am pasting the logs here.......

MSIASSERT - 2009-11-09-11-59-49-437 : cc::StopServiceAndDepAtAnyCost(366) : Unable to openService ccSetMgr. Error=1060:
MSI (s) (D8:CC) [11:59:49:437]: Executing op: ActionStart(Name=InstallLiveUpdate_RB.FF07F38E_78C2_412E_B858_64488E808644,,)
MSIASSERT - StopCcSetMgrOnOverOrBrokenInstall: Unable to stop ccSetMgr:
MSI (s) (D8:CC) [11:59:49:437]: Executing op: CustomActionSchedule(Action=InstallLiveUpdate_RB.FF07F38E_78C2_412E_B858_64488E808644,ActionType=3329,Source=BinaryData,Target=UnInstallLiveUpdate,CustomActionData=C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\QARXINZL\LiveUpdate\lucheck.exe)
MSI (s) (D8:CC) [11:59:49:453]: Executing op: ActionStart(Name=InstallLiveUpdate.FF07F38E_78C2_412E_B858_64488E808644,,)
MSI (s) (D8:CC) [11:59:49:453]: Executing op: CustomActionSchedule(Action=InstallLiveUpdate.FF07F38E_78C2_412E_B858_64488E808644,ActionType=3073,Source=BinaryData,Target=InstallLiveUpdate,CustomActionData=C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\QARXINZL\LiveUpdate\lucheck.exe)
MSI (s) (D8:5C) [11:59:49:468]: Invoking remote custom action. DLL: C:\WINDOWS\Installer\MSI7B.tmp, Entrypoint: InstallLiveUpdate
LUCA: InstallLiveUpdate enter.
LUCA: C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\QARXINZL\LiveUpdate\lucheck.exe
LUCA: InstallLiveUpdate : CreateProcessAndWait( LUCHECK.EXE ) returned 1
MSI (s) (D8:CC) [12:00:04:640]: User policy value 'DisableRollback' is 0
MSI (s) (D8:CC) [12:00:04:640]: Machine policy value 'DisableRollback' is 0

Regards,
Monica

First install lusetup and try to install sep afterwards.. 

Ya....that also has been tried.....Even then no result......

 have you deleted the folders suggested earlier and cleared the %temp% before the install ?

Troubleshooting Symantec AntiVirus Corporate Edition and Symantec Endpoint Protection installations: Checking rights and permissions 

While you are trying to install liveupdate whether it is getting installed? 

Is it roll backing the same place with same errors? 

After installing live update.....while running the av setup..in the task manager the LU* processes are running.....but after that it is not proceeding any further....the system hangs....

While running lu if you try to install sep the possibility of rolling  back is high..
Try to install after killing all process of lu.. 

Try to use Cleanwipe.

 Well the logs gives a very generic error that install failed due to liveupdate...I would recommend you download MalwareBytes update it and run a full on this system first..
As you had some problems with this system so you had removed SEP....

If the computer comes out clean..
then try installing SEP if still doesn't install try running lucheck.exe from Cd1\SEP folder and post the
luresult.txt

Also try running Cleanwipe once..

Well...Thats the easiest  way of resolving things when you need the issue to be resolved immediately..

Need to fully uninstall SEP 11.  Need Cleanwipe.  Thank you.
Support #100120-001480

Though its fixed, I suspect Sality's hands in this... It just messes around big time.. That's why when in doubt, don't ever try to do repair or removal of the AV product... :) ... Anyway, good that things are fine here..

Cheers,
Visu.