HP (Hewlett-Packard) h5400 ユーザーズマニュアル

From the program you would like to minimize, tap the X in the 
top right corner.

Programs may close automatically as you open new programs. 
This will depend on the amount of RAM being used.

If your iPAQ Pocket PC is running slowly, you can manually 
close programs.

To close a program:

1. From the Start menu, tap Settings.

2. Tap System, and then Memory.

3. Tap the Running Programs tab.