You application will work a lot better if you don't delete the domain account we use for running it. Yes I do know you can recreate it, and give it exactly the same name, but it will have a different internal id and that is what the security system uses when checking access rights. Still I didn't have anything else lined up for today apart from going to the dozen or so servers and setting the userid and password on all the services that use this account ... and all the batch jobs.
In fact I am amazed that the application is running at all, and you should thank your lucky stars that the several thousand people who are using it right now are not all phoning your helpdesk!
Peter