Hello,
Allowing all autorun.inf files is a security hole, a workaround would be to create a policy in a SEPM (if available) allowing specific devices through the rule.
In your case, since you have an unmanaged SEP client, you can either uninstall the Application and Device Control from Add / Remove Programs.
OR
Disable the Application and Device Control Policy by following the steps:
- Open SEP Client user interface.
- Click on "Change Settings".
- Click on the "Configure Settings" next to Client management.
- In Client Management Settings screen remove the checkmark for "Enable Application and Device Control"
Reference: http://www.symantec.com/docs/TECH181428
Hope that helps!!