DV50 mov files crash

[sophocles]

Even running the VapourSynth Viewer, without opening a file, I get an error:

Failed to open the file C:/Users/USER/AppData/Local/Temp/tempPreviewVapoursynthFile09_13_24_852.vpy.

There is no such file, but also don't know why it's looking for it before I load a video....  

Thanks!