If you have the exact same problem, you ought to know!
Seriously, guys, we need more information. What did you do? What did you expect to happen? What happened instead?
If this is "the 16-bit problem", even I can't blame Microsoft for it. When we put the CPU in "long mode" (64-bit), "v86 mode" (which is what WinDOS has been running in for ages) is no longer available. Blame AMD, I guess, or perhaps the laws of physics. AFAIK, 32-bit programs should run in 64-bit Windows. That would include Nasm itself - I don't think we provide a 64-bit build of Nasm. There may be issues I'm not aware of. Tell us about it!
You should find 64-bit examples in the "Example Code" section (mostly thanks to Encryptor256 - Thanks!).
As "Number Five Is Alive" says... "need input", "need input"...
Best,
Frank