The setting in the BES IT Policy that is doing this is 'Enable Long-Term Timeout', which states:
"Specify whether the BlackBerry device locks after a predefined period of time, regardless of whether the BlackBerry device has been idle or in use during that interval."
You could ask your BES Admin, nicely, if they can remove this setting from the IT Policy.... as long as you already have the forced password, this seems overkill, IMO.
Unless you work for the government.
