HTTP error on image upload

On the latest and greatest WP version, but cannot upload pics to my gallery, via two different browsers. I get a HTTP error on upload, and its on a hosted site, so can log a support ticket with the host if need be… where should I start looking, is there a log file I can post to help?

This happens both with Safari and Chrome on OSX, and nothing more than a ‘HTTP error.’ when it tries to upload.