Logged-out guests aren’t able to upload attachments for security reasons. You can use a service like Imgur to share you screenshot.
Also, could you confirm that’s it not freezing on start, but actually freezing during the early moments of a scan?
Lastly, could you please try to run System Ninja in debug mode (Option -> Settings -> Run in “debug mode”). This will produce a log file in System Ninja’s directory which you can copy/paste here.