Project Save Error and Corrupt Exports

I keep trying to export a 3 minute video, but when I play it back, each time there is a new issue with it -- the music track cuts out 10 seconds in but all the other audio remains, and/or a graphic that I added is not there, etc... After each "corrupt" export I check the sequence every time and the graphic is there and the whole music track is there.

I'm also getting messages saying my Recovery Image (D:) and "target disk drive" are low on disk space, and so it tells me "save as" to a new destination, but I've done that multiple times and there's still the same problem. I've noted that sometimes along with the export will be an mp4._00_ file, which I've never seen before. I'm doing nothing different than what I always do (1080 h.264 export 10-14 variable bit rate, vimeo preset). Would it have anything to do with my driver? I recently updated it, but I may have selected the wrong type to update??

Specs: Windows, ACPI x64-based PC, NVIDIA Quadro M4000, Intel(R) Xeon(R) CPU E5-1650 v4 @ 3.60GHz