Hello,
I've got an issue seems similar.
I'm creating a new project called New Project 1 by default. I'm playing around with(loading kit, changing instruments), then I save the work with an another name like _My_Project.
When I'm loading a new project called New Project 1 by default spark software is freezing, I can see the windows spark.exe stop running then the app is closed by windows.
My controlller is frozen too on my last saved project.
When I reboot my pc the controller is still frozen, I've to power off then power on to get the controller working.
I'll test to uninstall my controller driver, reboot, then reinstall it, for the software too.
I'm currently running windows 8 pro x64 in a domain network without GPO or something else and i'm a local admin with UAC disabled.
I hadn't theses problems with latest beta.
I hope this help
Greetings.