I am using auctex in Emacs, and upon running Preview->Buffer (C-c C-p C-b), what happens is:
- Triangles with red borders and white interiors replace every math formula
- A white and empty Ghostscript command prompt pops up
- Back in Emacs, the bottom line suggests "Type 'C-c C-l' to display results of compilation."
- So I do "C-c C-l", and I see many sections like
 !Preview: Snippet 7 started. <-><-> l.49 \item An observer can go from $p$ to $q$ !Preview: Snippet 7 ended. (338603+152916x386477). <-><->
It ends with
Output written on _region_.dvi (35 pages, 7212 bytes). Transcript written on _region_.log.
TeX Output exited as expected with code 1
Preview-DviPS finished at Sun Jul 3 00:47:34 Running `Preview-Ghostscript' with ``"c:\Program Files\gs\gs9.19\bin\gswin64.exe" ^"-dOutputFile=^(_region_.prv/tmp6592tSU/pr1-^%d.png^)^" "-q" "-dDELAYSAFER" "-dNOPAUSE" "-DNOPLATFONTS" "-dPrinted" "-dTextAlphaBits=4" "-dGraphicsAlphaBits=4" "-sDEVICE=png16m" "-r103.431x103.742"''
After this, if I close the white Ghostscript command prompt, then the buffer updates and says that Ghostscript exited abnormally with code 255.
What should I do to solve this problem?