No sound coming from software instruments on Pro Tools SE 8.0.3

[taylor6192]

Hello,

I am fairly new to Pro Tools, so when replying with an answer please assume almost no knowledge of the software. I am running Pro Tools SE 8.0.3 with my M-AUDIO Fast Track on my Macbook 10.8.5, Processor: 2.66 GHz Intel Core 2 Duo, Memory: 4 GB 1067 MHz DDR3.

In the past when using Pro Tools, I was able to create a new track, then select a software instrument and play the instrument by opening the MIDI Editor and clicking on the keys of the piano.

Recently though, when trying to do this, I receive no sound from almost every software instrument. The only software instrument I seem to receive sound from is the Church Organ. For the rest of them though, when I click on the piano keys there is no sound output, even though the notes show up on the track as if I have added them.

Does anyone have a solution to this problem? Is there a simple option somewhere that I can adjust to fix it?

Thanks,
Taylor