How can I forbid user to change clock of pocket pc

Archived from groups: microsoft.public.pocketpc (More info?)

My progject based on pocket pc and vb.net have to resolve some security
problem, Now ,I have met two difficutites as follow:
1:because employees are requireded to finish their work(use off-line pocket
pc) in time,so we forbid employees to change clock of pocket pc.I don't kown
How to do it althrough I thought about it for long time.
2:Because security requirement, when Employee lost his pocket pc, My
program must delete all important data. so I want to develop a screen
protect program which like settings password of pda,when device unused for
some times,my program require user to log on, after fail to log on three
times ,My program delete all data. I have searching for the document about
it for several days,but I did't found it.
someone please remind me to resolve the two problems!
thanks in advance!