I queued up Mashable.com at 10:50 am cst and received the above error. According to Google, Malware is detected on Mashable.com.
Warning: Visiting this site may harm your computer! The website at mashable.com contains elements from the site cdn.eyewonder.com, which appears to host malware – software that can hurt your computer or otherwise operate without your consent. Just visiting a site that contains malware can infect your computer.
There is a lot that loads when joinning any page and Mashable and any website can add things to their site that haveunknowingly been flagged in Google for malware, but nonetheless, proceed cautiously when you see this error.
I cannot in any way see Pete Cashmore of Mashable fame knowingly allowing any form of malicious content on the site, but none the less, a warning from Google is pretty strong.