iBook - Ibook G4 has started to switch on without pressing the power button

My Ibook G4 has started to switch on without pressing the power button. It does this if I don't disconnect the battery. There is no intervening software and wireless is turned off. Any ideas what is the problem?

Other thing is that occasionally when browsing Firefox and when trying to open new pages, the machine refuses and instead wants to save the wanted web page.

also occasionally my keyboard goes all funny and when trying to type something, instead of normal characters, strange foreign characters appear. Once I close Firefox and restart, keyboard is working fine. There has been no water etc. damage.