Help on deciphering crash

[David Melman]

Our Vax 750 running 4.2BSD has occassionally been crashing with:
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machine check 2: cp tbuf par fault
	va 80039728 errpc 8000394e mdr a smr 8 rdtimo 0 tbgpar 0 cacherr 5
	busserr 6 mcesr 9 pc 8000394e ps1 40c0008 mcsr 80016
panic: mchk
panic: sleep
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Where do I start to find the problem?

Thanks,
David Melman
UNISYS
UUCP: {hplabs, ihnp4, cbatt}!sdcrdcf!davem