Your initial command was "\\server\ezaudit\ezstart.exe". Then you say you mapped the drive to "Y:", and then ran "\ezaudit\ezstart.exe". Isn't "ezaudit" the share name? If it is, all you need to do is go to the ROOT of Y: and run "ezatart.exe" with your args. However, if "ezaudit" is not shared, it would explain why none of the UNC paths work.
What is the server name?
What is the share name?
If you map the drive to that share manually, what do you see when you run DIR? (post the actual command output, please)