Hello Robert,
I checked my SEP 12.1 unmanaged client and I do not see any options for disabling ActiveScan on login. Are you seeing ActiveScans occur when users login?
The unmanaged SEP client is more limited in what can be configured than the managed client. If you need to change a setting in the unmanaged client which is not available in the unmanaged client's GUI, you have two options.
Either 1) make the client managed or 2) configure a managed SEP client (using the SEPM) exactly how you want it, export the policy from the managed SEP client, and import it into the unmanaged SEP client. Option 2 is cumbersome and involved, but it works.
If you need more details on this, let me know.
James