is the lid closed or open?
There is not a lot of information to go on here.
If the lid is open, see if you can replicate the problem by lifting the iBook about an inch up from the desk, slowly. If it is still on, gently flex the base. Did it sleep?
It is actually safer for the machine to be asleep during any move as the HD heads move back to their parked position and sudden jolts do not cause the heads to contact platter surface and damage it.
Another thought comes to mind, is it running on battery power when you move it? Could we be looking at something coincidental here. Is the iBook set to go to sleep after so many minutes of inactivity and is about to sleep when you move it? Is this actually Sleep or is it just the screen saver that comes on? Is there any noise from the machine when it is "asleep"? HD spinning, fan running etc.?
Does it go to sleep when the AC adapter is plugged in and you move it?
P
I have an iBook 600Mhz and for some reason if i am using the i book it works fine but when i pick it up while it is still on it just goes to sleep and then i have to press any key to wake it up. Does anyone know why my iBook does this?

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