It seems File2box plugin not working correctly without captcha. I am not sure why the captcha verification is removed from file2box website, it may be due to the captcha server problem, or it could be file2box website's policy change, or even a happy hour? :) Here is the detail info.
Freerapid: 0.83u1
File2box plugin: 1.0.3
Error: Captcha not found.
Sample url: [
www.file2box.com]
just in case, the problem may be gone at the moment you try to investigate, I have the sample url screen captured and webpage saved as text for code analyzing purpose. Hopefully it can be a help somehow.