Windows 8.1 Movie Maker audio problem

I am having major problems with audio on my Movie Maker. Before I updated to Windows 8.1 it seemed to work fine, but after updating when I'm editing in Windows Movie Maker the audio will sometimes disappear. Not just in Windows Movie Maker, but on the entire computer. Not muted, nothing comes up in diagnostics. I uninstalled and reinstalled movie maker (rebooting computer in between for good measure). The problem still persists. If I reboot my computer the sound will come back, but if I start trying to edit the same video again it will putz out again after a short while. (This has happened on multiple videos I've edited so I'm sure it's not just a specific faulty video).

Please help. I've been trying to figure this out myself for over a month. I've tried all the solutions I can think of. (Oh, and please don't post any youtube video solutions, it's really hard for me to get onto youtube because I'm currently living in China).