Is that true for any file -- including a super basic one with one citation -- or only a specific one? Which software do you use to generate the RTF file?
And also to be clear--by "crash" you mean actually close down, yes? Not just freeze? An RTF for a large file would likely freeze Zotero/Firefox for a while, including with a "non responding" message.

@Dan - what does the error report say?

Pinging this issue - I get this result when I try to do rtf scan from Zotero standalone. It's a proper crash where the program just dies and I get the standard Windows message asking me if I want to report it to Microsoft.

It seems to be getting through most of the process before crashing - for instance it asks me to resolve ambiguous citations which I presume means that it's done the pattern matching OK. It crashes on pressing the next button after selecting citation style

The particular file I'm using is quite large (65MB) and contains pictures.

Happy to provide information to help debug if I can.

System details: Zotero 4.0.26.4, Windows XP 2002 SP 3

N.B. I'm trying the same thing in the browser (Firefox) version where it seems to be getting further - I'm now waiting on a (Formatting citations) screen where the green bars are still rotating left to right so it seems to be processing, but it's taken 9 minutes so far.... (EDIT: 45 minutes - I guess it's hanging - I'll stop it if it gets to 2 hours)

Yeah - I was wondering that, too. I'm trying to isolate the cause by taking the pictures out bit by bit. Interestingly - if I open the original RTF in OpenOffice now, it seems to have field codes in it. I wonder if my RTF is from a file that had zotero codes in the first place. I'll post here if I get any further.