Same thing has been asked before, check here for help:
http://www.kristensboard.com/forums/index.php?topic=23978.0Basically, you either have an AdBlock-style add-on running in your browser that's killing the Google reCaptcha, or some malware that's intercepting the URLs. See my note on downloading and running ADW,
http://www.bleepingcomputer.com/download/adwcleaner/as that's the most likely to clean you up in case of a malware infection. If it's an AdBlock, then simply disable it while you're doing a submission. You may also have Javascript disabled, which will utterly kill the reCaptcha.
I think the archive is still using v1 of reCaptcha, which you can test here:
http://www.google.com/recaptcha/demo/The v2 recaptcha has a little checkbox that says 'I'm not a robot" and then it leads you to either a text challenge or a picture challenge. That version has had lots of issues, and it's not very friendly to non-English speakers so most of us won't use it.