Symantec Endpoint Protection (SEP) Intrusion Prevention Signatures (IPS) are successfully downloaded but the SEP client fails to apply them.
Operating system is Windows 2003 Service Pack (SP) 1 or earlier or Windows XP SP2 or earlier.
There is a compatibility issue between the OS and the IPS driver, IDSxpx86.dll.
Update Windows 2003 to SP 2. Update Windows XP to SP 3.