ASP.NET is a necessary account setup by .NET Framework.
You need this account. You could try a reinstall .Net Framework or all Windows Updates.
You could also uninstall .NET Framework and then reinstall etc.
Anyway you have removed a vital account that needs to be reinstalled.
If you have a System Restore to a Clean Place after your work with
Neal you might try that.
Beyond this here is another page:
How to take ownership of a file or a folder in Windows XP