ASP.NET 2.0: ACCESS DENIED to resource when trying to impersonate a local user account

Hello,

I am working with GnuPG to encrypt comma delimited text files, that will be sent via FTP client programmatically.  I am using C# w/ASP.NET 2.0.  The software works without fail on my XP Pro machine, but when I move it up to my Windows 2003 server w/SP1 it is unable to encrypt the text file and output it to the directory I specify.  Specifically, I start up a process, passing in my ProcessStartInfo which contains the location to the gpg.exe, the arguments, and properties to keep the window hidden. 

While troubleshooting, I ran "FileMon" to see if I could see a specifc file access error, which I did.  The process is trying to access "C:\Documents and Settings\Default User\Application Data\gnupg".  The error line in FileMon reads:
9:47:37 AM   gpg.exe:3960   CREATE   C:\Documents and Settings\Default User\Application Data\gnupg   ACCESS DENIED   NT AUTHORITY\NETWORK SERVICE  ...