I've seen this problem in the past. I doubt that flashing to v2.2 will solve the problem, but he may as well try.
It's a defective Grex1200 unit. You most likely need a new Grex1200 logic board (the piece that connects the PPC card to PCI slot board). Speaking from personal experience. :-)
One last thing to try would be to put Voodoo in PCI slot #5 and see if that makes any difference. You don't need a DMA capable slot for Voodoo 3, so in general don't use it in slots 1 or 2.
