I've made some changes to the feedback service today. It should be working more smoothly now. It used to time out for a lot of users when it grabbed a list of feedback you've already left.
I no longer look for feedback you've already left, as this really isn't all that important to the service.
If you're not sure if it's working or not, you might want to consider turning on the email notification summary results. You'll then get a message each time your account is processed, which should be once per day.