Well, I've tried installing ToH 10.5 RC2... as far as I remember (it was quite a while ago) this never used to have any problems like I am experiencing now - but currently it is suffering from the same issue.

I'm starting to think it must be a hardware problem using AHCI on my motherboard - I only ever use this option when booting OSX - normally I boot with RAID.

The strange thing is that OSX installs just fine, there are no stalls during the installation - only when finally booted into OSX and making "heavy" write operations - like copying a largish file etc.

From the lack of reply's it looks like I'm on my own with this one!! Maybe I will look into replacing the Motherboard

Anyone recommend a good one (Socket 775) that is compatible with OSX - I was looking at DFI IP45 mobos. I want a good overclocking mobo for use with windows - it may even be nice to be able to run two gfx cards (not SLI) I have a 8800GTX, but my main card is a GTX 275 - however this is not supported within OSX yet.

Any ideas?

Cheers,

Jon.