PowerISO, missing virtual drive.

This is probably something very simple that I'm missing, or did wrong, but I can't figure it out.

I downloaded PowerISO onto me laptop so I could play Assassin's Creed from the ISO I ripped since the CD was horribly scratched and my drive would not read it. Everything worked Perfectly until lastnight. I fired up the laptop and went to mount the AC ISO, right click the ISO>> PowerISO>> Mount media into Drive E: (My virtual drive). That worked fine, so I went to MyComputer to run it, but my virtual CD Drive (E was not there. I found it odd, that the drive wasn't showing up, or that PowerISO was no longer running in the background as it always has been. But, that I could still mount media to the drive. What happened? Would it fix it if I uninstalled then reinstalled PowerISO?
Thanks,
Spock96