Truths Revealed:
When you hit the X button, it just minimizes the program... And the app still takes up memory and processor.
You need to get SPB Pocket Plus, which fixes your problem and some other problems:
http://www.handango.com/PlatformProd...=50351&R=50351
By default, tap X to really close, slide the stylus from the X downwards to minimuze, and tap and hold the X to bring up a 'task manager'-like box