Netapp's given me 5.1.2P1 in hopes of it fixing things. Luckily for us, the box needed it's nightly reboot *after* getting that on there. I'll let you all know if this fixed things.

Nope, 5.1.2P1 also has this problem. We're downgrading back to 5.0.1D4. They've been no help yet on the core files, so I think that's our best bet.