Start up applications

I have a custom application that requires to be robust enough to recover from
a power outage and return in full operation. If the power is removed from the
PC and then restored, my application comes up and stops. Vista Business
returns Permission denied. If I do a controlled shutdown or restart of Vista
while my app is running I have no problems after the restart. Does anyone
have any idea why this happens only when I lose AC power? FYI.. the
application and user account has full admin rights, folder privlages etc..
Any help at all would be appreciated.