MY A64 3200+ has an unlock multiplier, I think. Is that normal?
It should be unlocked between 4x and 10x. All of the Athlon 64 CPUs I've run across are unlocked from 4x on up to their top multiplier (in your case, 10x) so that Cool 'n Quiet can work. Some BIOSes look like the CPU multiplier is unlocked upwards too, but it's actually not. If you try to set it at 11x or 12x or whatnot and reboot, the computer will boot up with a 10x multiplier instead. I suppose this is a quirk of some boards' BIOSes. The Award BIOS in my abit KN8-SLi has this behavior and my X2 4200's multiplier is certainly locked at 11x like it is supposed to be.
I have the option of up to 25x, although I haven't tried actually setting it and booting.
You can try to increase the multiplier and see if it will boot. I highly doubt it'll do anything, but what the heck. I'd try something like 11x just in case your chip actually did escape the factory with an unlocked multiplier. A multiplier of 25x would set the chip's clock speed to 5 GHz, which means it'll not even boot and you'll have to clear CMOS and reset the multiplier to get it to boot again.