This is caused by the computing power of your pc...sampletanks drags and demands power...if you dont have it to provide..the software is basically useless...why?...because you cannot tinker with the tons of buttons on that thing the fx's, the stretch engine, and my favorite the layering of instruments...once you mess with any of those mostly the stretch engine that holds or shapes the sound of the instrument if your computer dont have the power it'll either freeze, crash your computer...in your case your lucky it's only holding the note...Solution when you load the instruments especially like strings or symphony instruments leave as is....which defeats the purpose of the software... once it goes crazy remove the instrument and try another keeping the default settings and removing the fx's....