(Note, this is without a domain.)

I used to be able to type start \\other_machine\c$ in PowerShell and explorer would pop up with a login dialog. Then I'd type other_machine\moswald and my password (the account is a local admin, of course) and I'm in.

Now both machines have Windows 8 installed, and this no longer works (the dialog re-prompts with an "Access is denied" displayed). I've verified (through whoami) that the user is named other_machine\moswald, and I'm positive I'm typing the correct password.

So what gives?

(edited to include specific result)