The resource PC you use to run the Login process cannot run a 'normal' process. This resource pc runs in the 'system space', ie before the machine is logged in. What you need to do is have another resource pc start after the machine is logged in. Normally this is done by placing a shortcut in the Windows startup folder. This 'second' resource pc is the one which should in your process. This should be the sequence of events.
Machine boots up, login agent service starts, background resource pc starts
Login process is run on the background resource pc
Machine logs in
New 'user space' resource pc starts, old 'system space' resource pc closes down
User process runs on new resource oc