I have both MS12 and 13.
had this issue before, but now it's back.
I "make movie" and after the render it "says" it's a .mp4 but it is not.
The extension is a .tmp
I read the one post about this, and have turned off all virus programs, etc.
Same issue.
Help...........
Tried 7 times to render both in ms12 and ms13.
This has come up before but has not been answered to a reasonable level.
I even went and did a update for build 932 the most recent version.
Nothing... still doing it.
MS 12 and 13 noted in post. (Movie Studio)
Build number on post. (932) which is the most recent.
Did not put Windows 7 64 on the post.
You just have to read.
Also, if you'll read the comments on the video I posted the issue is known by MANY.
However, it has never been addressed "properly" on this forum.
While it's not a FIX for the issue, it at least gives you a way out of the TRAP.