Hi My macbook has always worked impecably. Today I had firefox and entourage crash, so I restarted. It wouldnt start, and now I cant turn it on. It turns on, and then either at the grey screen stage comes up with the compulsory restart warning, hangs at the blue screen, or very occasionally starts into leopard and immediately gives me the compulsory restart screen. I have a standard mscbook and havent installed any software recently nor dont anything major. I have reset the PRAM and now it is hanging at the first grey screen and not doing anthing!! Anyone help?? thanks so much! This is most distrssing and apple support is closed! i dont know if this helps I just did the hardware test and got an error with error 4MEM/1/40000000: 0859b5c4 thanks so much for the hep!