What OS? It could be a 32 bit vs 64 bit addressing thing.

How does it go with with 4GB of memory?

Have you swapped the 3 memory sticks in individually to make sure they are all OK in isolation?

Other than that I'd tip a power supply issue.
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Christian
#40104192 120Gb (no longer in my E36 M3, won't fit the E46 M3)