Thanks for the reply. I'm using version 5.1. I do have the Tools > Preferences > Backlight option and have set that to "Backlight on", but it doesn't override the 2 minute Blackberry setting - the screen still turns itself off after 2 minutes. Very annoying! I take it you've set your TeleNav to "Backlight on"? And it overrides your BB's setting of 2 minutes? Or can you set a different length on your BB?
Incidentally, my BB also locks itself after 2 minutes (at the same time as it dims the backlight). I've been trying to see if this is a different setting (e.g. under Security) but haven't found anything. Does anyone know if there's a setting that sets automatic locking of the handset after x minutes?