So the two Sun Engineers came out yesterday to watch the Oracle installer. Here's the wierd thing. Even though almost every possible piece of hardware had been replaced in that box over the course of the last two weeks, the Sun 'experts' decided to replace everything again - only this time do it all at once.
Seemed strange but they obviously knew what they were doing as the Oracle installer ran like a charm - no more crashes. I heard a really loud 'Yeeees' from our DBA's cubie - there were grins all round