Acrobat should not crash and I can't help you fix it, but there is a contradiction in what you describe. It may be that because of this, you don't need to do what you are doing. Here's the problem. You say you "convert to PDFX". Somehow. I assume you mean one of the PDF/X versions such as PDF/X-1a or PDF/X-4. ALL versions of PDF/X require that all fonts are embedded. There are no exceptions to this. So if you have a PDF/X file of any kind, and it was made by correct software, then all fonts ARE embedded.
Perhaps the problem is how you are making the decision. You say "does not have any fonts embedded". How do you decide this?
Thanks for your response. You are correct, I am converting a PSD file to PDF/X-1a by selecting save as and choosing the corresponding PDF preset. When I open the newly created PDF file, and check the fonts (command+d) no fonts are listed, which I found bizarre. So I decided to run the pre-flight to fix this problem. However, the pre-flight will not run smoothly for some reason. I also ran the pre-flight to check for PDF/X-1a compliance and got the green light, yet no fonts are listed?? Which to your point, is contradictory. I am at a loss. Any suggestions would be appreciated. Thank you.
If no fonts are listed, at all, by Ctrl+D, then there are simply, no fonts. All the text was rasterised or turned into curves by Photoshop. This cannot be rescued by any amount of preflight, and it is not incorrect (because when there are no fonts, there is nothing to embed) even though it might (or might not) give poor results on printing.
A more usual workflow if there's any serious amount of text would be to add the text in InDesign and export PDF from there.