So I found this old NEC Versa V/50 laptop buried in my closet and I flipped on the power switch to see what it would do. It seems to be working fine, but the CMOS battery is completely dead and it complains about changed or corrupted settings every time you reboot. I normally just hit the button to activate the factory settings. I can't get farther than POST though, because when I insert a perfectly good DOS 6.22 boot disk, it reads from the disk for a second and then says that a boot method could not be found. On those occasions that the CMOS manages to get the hard disk right on the first try, it says "Starting MS-DOS..." as if it expects it to be on the hard disk, but then complains of a bad or corrupted command interpreter. I'm all too happy to point it towards the COMMAND.COM residing on the floppy disk, but again, it accesses the disk for a bit and gives me the same error message all over again. How can I get it to boot from the accursed disk?

P.S. Opening the hard drive compartment reveals a 3V lithium "button battery" mounted above the disk. I'm not entirely sure this is the CMOS battery, but since I should be able to get a replacement for only a couple dollars, I figure it's worth it to give it a try. Though I don't see how this would solve the problem of not liking the command interpreter on the disk.

Weird problem, I agree. But I would change the battery first just to make sure that it isn't the problem. After all, the battery maintains the Bios' CMOS settings.

Got the battery replaced, and the CMOS saves correctly every time now, but it still has the same problem. Every time I boot it up, it's always "Bad or missing command interpreter", whether the disk is in the drive or not. If I point it to the command.com on the disk, it just reads from it for a few moments and then gives exactly the same message again. If I manually disable the hard drive in the BIOS settings, it reads from the disk for a bit on boot-up and then complains that a boot method could not be found.