Sp5 keeps switching back to homescreen

[Guest kc1]

With the homescreen timeout set to 10 secs, my Sp5 keeps switching back to the homescreen even when I'm using other applications (games/IE/TomTom), every few seconds (somewhere between 10secs and 1 minute I think, though I havent timed it)

I thought timeout was supposed to be if you weren't using the phone (ie. idle/no key presses or joystick movements)

Does anybody else have the timeout set to10 secs but without issues?