After getting tired of manually eliminating the nvram before each recording that is affected by the presence of nvram, I came up with a solution for me that may already be known. But, I thought I'd post it here anyway. I simply moved the nvram folder elsewhere other than under the usual MAME path. That is provided you want to preserve existing nvram files. Otherwise, and correct me if I'm wrong, you could just delete the nvram folder entirely for a somewhat permanent solution.
right, both of those ways work very well, moving or deleteing. luckily the mame programs (even back in earlier versions when nvrams where in their infancy) allow safe to delete/rename the nvram directory and mame won't crash and expect it to be there.