Hi,

If I've understood your problem correctly, simply using ("" "fontspec" 
nil) in org-latex-packages-alist should fix your issue.

Per the documentation, this third argument stops the package from being 
used when compiling preview fragments.

Regards,

Sébastien



Gabriel S. X. Smith writes:
> This is where my fix starts to come in. When org mode does the small
>
> export of the latex fragment it would include the contents of
> org-latex-packages-alist in the LaTex headers. Some packages (namely
> 'fontspec,' used for xelatex) would lead to a failure to create the
> dvi file when the .tex file was compiled with the necessary
> 'latex' command.
>
> To alleviate this problem I designed this wrapper function which
> sets org-latex-packages-alist to nil just before executing the
> org-latex-preview function.
>