I'm not sure about downgrading
but I see from Google that this has happened before.
Have a look at http://productforums.google.com/forum/#!topic/chrome/F10VPqExRCI and the different attempted options there.
A couple I noticed was Chrome's Incognito mode, and flushing the browser's history, cookies and TIF files.
See if that works on just one of your systems, (as a test).