So far, I've seen this error only because of an IRQ-Problem with an ACPI System, running pfsense on. It seems to me, that the realtek-driver is not able to share IRQ's under some circumstances with other drivers…
So, you might probably put the card in another pci-slot, and check, if the error occurs further on. Second, it may help to disable unneeded onboard components, as USB or LPT or a soundcard.