[dust2dust]

1 of two reasons i can see


1 magic boot procedure means the disk has to be read loaded by a certain time,so if your disk is hard to read then it cant focus fast enough to boot (u could try copying it on good dvdr then if its this your problem will be gone
2 magic2 origanal,cone1,clone2,clone3 so on ,depending which u have affects on how in performs (i doubt its this as it boots occasionally)