Vista - DEP disable for one program

Problem - we want DEP to be switched on for all except one program

We tried to install a program but the installation kept crashing
because DEP was preventing it from installing. We could not install
the program until we had disabled DEP globally. We found instructions
and disabled it globally using this procedure:

1. Ensured that we were logged in to Windows Vista Home Premium as an
administrator
2. Right clicked command prompt icon- selected 'run as administrator'
3. entered the command: "bcdedit.exe/set {current} nx AlwaysOff"

The program is now installed successfully and working.

Once the program was installed we tried turning DEP back on globally
using the same procedure as above with the following command:
"bcdedit.exe/set {current} nx AlwaysOn"

Once we had completed the procedure above we tried to access the
feature to disable DEP for one program only using the following
procedure:
1. Access the control panel
2. Select 'system'
3. Select 'advanced system settings'
4. Under 'performance' select 'settings'
5. Select 'data execution prevention' tab

However the option to disable DEP for one program only was greyed
out.

We then tried restarting the computer

On startup a Windows Error message popped up with the following
information:
(a picture of a windows box) has stopped working:
Problem event name: BEX
Application name: dsca.exe
Application version: 1.0.2767.18581
Application timestamp: 46ae0f8b
Etc...

In the taskbar a small window popped up saying: "To help protect your
computer DEP has closed"

Going into the DEP settings through the control panel, the options to
enable/disable for only one program were still greyed out.

We then disabled DEP again using "bcdedit.exe/set {current] nx
AlwaysOff"

Now that we have the program installed, how can we first enable DEP
globally and then disable it for that one particular program?