I’m having similar issues. Just started happening today on HostGator.
Warning: file_get_contents(https://alamoxie.com/wp-content/plugins/backwpup/job/job_run.php) [function.file-get-contents]: failed to open stream: HTTP request failed! HTTP/1.1 404 Not Found in /home/alamoxie/public_html/wp-content/plugins/backwpup/backwpup-functions.php on line 732
This same error started happening on ALMOST all my HostGator sites (which are all on the same server). I’m not sure why a few were not affected. If I completely uninstall and reinstall the plugin, it seems to work again, but that may just be temporary.
I’m on HostGator too and had the exact same problem, but I got locked out of the Dashboard! Had to log into the server filesystem to delete the plugin the old-fashioned way…