I know you probably don't want to hear it but..
I would look no further than your "
Echo Layla24 " as the root of your problem.
PCI soundcards began to fade out almost 7 years ago.
A good read:
http://forum.cakewalk.com/Is-it-time-to-give-up-on-the-Echo-Layla-2496-m2919657.aspx Melodyne has been solid here. I don't even think I've ever had a Melodyne related crash, but I always render a clip as soon as im done editing it in Melodyne.
There is a bug however, when using Region FX and the transport is rolling that is driving me bananas.
Seriously though, obsolete soundcard, bluescreen, crashes = try a different soundcard.
Heck even do a small test, remove the soundcard and use MME or WASAPI and see if Melodyne crashes.
Sonar uses resources for Melodyne.