Had this response from Samsung UK on Facebook earlier, at least they're acknowledging the problem and doing something:
My S3 crashes every time I try to copy & paste something. A quick google has shown this to be a massive widespread problem, when are you going to issue a fix for this?
Samsung Mobile UK
Hi, we are working on it as I type - not sure when this will roll out but it will likely come in the form of a stability update to Jelly Bean. Thanks for your patience with this and stay tuned for updates. ^George