Been having a problem with my iBook for a while now.
Sometimes when i take the charge cable from the iBook,
when fully or partially charged, the computer immediately
turns itself off and will not restart unitl the power cable is
reentered (even with a full battery etc). This will then have to
stay plugged in for upwards of 10-15 to solve the problem.

It sounds like there are power problems inside your iBook.
If the power adapter only glows green then you know this
for certain. It should glow amber when the battery is
charging. You can also test you battery's capacity by
flipping the computer over or just looking at the bottom
side and pressing the button somewhere on the battery
face. Little LEDs should glow indicating the battery's
current charge with more lights indicating a larger charge.

If this is not the case and the computer is still under
warranty I would recommend having an Authorized
Service Center look into fixing it. Generally this problem
is a bad DC-in board (where your power adapter plugs
into the computer) but on rare occassions it might be
either the battery or logic board itself is bad.

Good luck!