executing a bat file with a gpg command

We have a vb.net filesystemwatcher that monitors a FTP directory. When we
receive a file in that directory we run a bat file that contains a gpg
command that decrypts the file.

This process has been running great for better than 6 months. Suddenly, it
quit working in that it will execute every line in my bat file except the gpg
command.

When running the bat file manually (double clicking the bat), the gpg
command will execute and process just fine. But when we call the bat from
VB.NET, it won't work.

Has any ran into this issue and if so, how did you address it.

Thanks for any help you can provide,
--
Tyler