While trying to install (or re-install) the Symantec Management Agent (aka Altiris Agent), the following pop up messages appeared:

AeXAgentSrvHost. This service could not be started.

OR

AltirisAgentProvider. This service could not be started.

Most of the agent components seems to be installed but the Symantec Management Agent,  AeXAgentSrvHost, or AltirisAgentProvider services are not installed.

These were the error messages while trying to reinstall the agent (look at the Install Logs under C:\ProgramData\Symantec\Symantec Agent):

2017-05-09 12:17:46 P:2664 T:1896 *ERRR Altiris Agent: Failed to unregister type library '2' for module 'C:\Program Files\Altiris\Altiris Agent\AeXNSAgent.exe', error: Error accessing the OLE registry (0x8002801C)

2017-05-09 12:17:46 P:2664 T:1896 *ERRR Altiris Agent: Failed to unregister service: Error accessing the OLE registry (0x8002801C)

2017-05-09 12:17:47 P:2592 T:3672 *ERRR Installer: Failed to perform custom action, exit code 0x8002801C

2017-05-09 12:17:52 P:4220 T:4112 *ERRR AeXUtility: CreateService('AeXNSClient'): Failed to create service, error 0x00000002 (The system cannot find the file specified)

2017-05-09 12:18:07 P:2592 T:3672 *ERRR Installer: Failed to perform custom action, exit code 0x80004005
 

We saw messages like these in the install logs when we tried to uninstall the agent:

2017-05-09 12:22:48 P:1424 T:4844 *ERRR Installer: Failed to perform custom action, exit code 0x8002801C

2017-05-09 12:22:49 P:2664 T:2732 *ERRR Altiris Agent: Failed to unregister type library '2' for module 'C:\Program Files\Altiris\Altiris Agent\AeXNSAgent.exe', error: Error accessing the OLE registry (0x8002801C)

2017-05-09 12:22:49 P:2664 T:2732 *ERRR Altiris Agent: Failed to unregister service: Error accessing the OLE registry (0x8002801C)

2017-05-09 12:22:50 P:1424 T:4844 *WARN RemoveDirectoryTree: Cannot delete file 'C:\Program Files\Altiris\Altiris Agent\AeXTemp.exe', error: Access is denied
 

ITMS 8.x

In this particular case we found out that McAfee Access Protection was enabled on this machine.
We opened the log for this process and this entry was noticed:

5/9/2017 12:22:51 PM Blocked by Access Protection rule C:\PROGRAM FILES\ALTIRIS\ALTIRIS AGENT\AEXTEMP.EXE C:\PROGRAM FILES (X86)\MCAFEE\VIRUSSCAN ENTERPRISE\MFEANN.EXE Common Standard Protection:Prevent termination of McAfee processes Action blocked : Terminate
 

Disable McAfee Access Protection and try again to install the Altiris Agent.