Schwinn exercise machines ...

I recently purchased a Schwinn elliptical machine, and for some reason I feel like it's a little off when telling me the amount of calories I've burned. If I run 30 minutes at the gym, I know I usually burn around 300 calories or more. With this machine, it seems to say double the amount I'm used to seeing, so it normally says 600 calories or more if I run 30 minutes, which is impossible for someone with my stats and speed of running etc. Does anyone who hasa Schwinn product or who has used a Schwinn product know what I mean? =S

I have the Schwinn elliptical machine and bought it 6 months back. I have stopped using the machine as it shows the wrong heart rate. While I was working out, it always used to show a higher heart rate and effectively higher calories burnt. I compared this by wearing a Polar HR monitor and it showed me my correct HR and also I burnt half the calories that the elliptical estimated.

Thank God it's not just me! I was so confused when I saw that I burned that many calories .. I'm like that is utterly impossible .. I think I'm going to call them in regards to this issue. It's really unfortunate, seeing as they are very costly, so you'd expect them to be a little more trustworthy in terms of accuracy!