StartSSL uses client side certificates to authenticate you. Last time I checked this only worked in Firefox. Perhaps that is the reason for your crashing.
Client certificates should work in all modern browsers. We use them daily in Chrome, Safari, Mobile Safari, IE and Firefox.
Chrome is reliant on the host OS certificate stack, unfortunately Chrome and client certificates don't seem to work well on OS X for this reason. Safari works, however.
btw it fails on latest chrome and firefox on mac but works great on IE 8/9