I found the following statement at www.pocketgamer.org
New Jornada: HP, we have a problem
Douglas Beck, author of RocketElite, has posted an interesting and worrying message in this Brighthand thread regarding a serious problem with the new Jornada 56x series that has been brought to his attention:
"The HP Jornada 56x will spontaneously stop reporting button presses through the GAPI. Therefore all games or applications that use the GAPI reading button presses will stop responding to any hardware button presses.
It is not known what causes this problem. It occurs fairly often considering it is something that should never happen. In the few days I was testing an HP 568 the device exhibited this behavior after only a few days of use.
It doesn't appear to be caused by any one particular user operation. Currently the only known solution is to perform a hard reset of the device. Also the device still operates normally and reports button presses for non-GAPI applications."
As if that wasn't bad enough, another problem is "that the HP 568 "Home" button does not report WM_KEYDOWN when pressed but only reports the WM_KEYUP when released. This "Home" button issue is a personal disappointment to users and developers alike because it renders the button virtually useless for game applications."
Douglas notes that "if you have experienced this problem yourself (and people have as I can see by browsing this discussion forum) or can offer solutions, I would encourage you to post."