virtual instrument tracks

Cubase LE5 on Windows 7 64bit.

When I setup virtual instrument, and select the instrument, I use the keyboard and the midi controller and i can hear everything fine. While I am in the project it plays back nicely. Once I save the file and exit, the program, then come back in and load the program, the virtual instrument no longer plays back. none of the settings have changed, but it no longer works. i have searched for answers and I am stumped.

Also, Halion one just disappeared. No reason, its just gone. I get so frustrated.

You should always check your audio ouput connections before starting a new session, as Cubase has a tendency to lose your driver settings each time.