SEP in configured. I have done many SEP\Altiris related installations, and at least default SEP settings don't exhibit this behavior. So you are going to want to check the Application Control policies, or the SNAC configuration depending on what you have installed.

Create a centralized exception to Tamper Protection

1. In SEPM, click Policies
2. Under View Policies, choose Centralized Exceptions
3. Under Tasks, choose "Add a Centralized Exceptions Policy"
4. Define the exception item (AeXNSAgent.exe by itself should work, but you may need to add path, e.g. C:\windows\temp\apt1\AeXNSAgent.exe), type (Tamper Protection File), and Action (Ignore).
5. Do this only if you're sure that Altiris isn't interfering with SEP11.  But I find that highly unprobable, so I'm sure you're golden to make this exception.

Please mark mclemson's reply as s solution if it helped you. Doing so helps everyone else who may be having a similar issue.

I know you can put an exception in but we should not need to put an exception for a Symantec core product,
It makes no sense.
SEP should not be resonding like this,
I have been out of country or would have responded sooner.

I recommend opening a support case.  Considering there's a KB called 'How to disable Tamper Protection so that it does not conflict with Altiris,' https://kb.altiris.com/article.asp?article=29500&p=1.