Did you do the following ?
1. Stop the "Symantec Endpoint Protection" service via services manager (services.msc)
2. Extract the contents of the 32-bit folder to a temporary folder.
3. Proceed to the "C:\Program Files\Common Files\Symantec Shared\SRTSP\" folder and rename the following files:
SavRT32.dll -> SavRT32.dll.bak
Srtsp32.dll -> Srtsp32.dll.bak
4. Copy SavRT32.dll from the temporary folder to "C:\Program Files\Common Files\Symantec Shared\SRTSP\"
5. Copy Srtsp32.dll from the temporary folder to "C:\Program Files\Common Files\Symantec Shared\SRTSP\"
6. Proceed to the "C:\Windows\System32\Drivers\" folder and rename the following files:
srtsp.sys -> srtsp.sys.bak
srtspl.sys -> srtspl.sys.bak
srtspx.sys -> srtspx.sys.bak
5. Copy srtsp.sys from the temporary folder to "C:\Windows\System32\Drivers\"
6. Copy srtspl.sys from the temporary folder to "C:\Windows\System32\Drivers\"
7. Copy srtspx.sys from the temporary folder to "C:\Windows\System32\Drivers\"
8. Start the "Symantec Endpoint Protection" service via services manager (services.msc)
9. Make sure that the "Symantec Endpoint Protection" service starts successfully.
10. Reboot the computer.
Also please let me know the features installed of Symantec endpoint on your XP machine and on the Windows 2008 machine.
If you have installed the Network Threat Protection, Pro Active Threat Protection on any of them....then please go to the control panel..add/remove programs and uninstall these features. Try it only on one test machine
If you face any issue in uninstalling these features refer to this link.
http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007110814373848
Thanks
Sandip