Windows 7: Virtual XP Login Question

I've set up Virtual XP machines on my developers' computers so they can continue to use VisualAge Generator. To do this, I did have to join the XP machine to our domain. I've gotten it set up that when they click the icon for the program on the Win 7 desktop, it launches the XP machine in the background then opens up the app.
I have one machine that prompts the user for her password every time it launches. I've had her enter her password and check the "remember credentials" box, but it still prompts her every time. None of the other machines does this.

What could possibly be causing this to happen?

These machines are running 7 Enterprise 64 bit.