“unknown user, incorrect password, or login is disabled. Please retype the login information or contact the disk’s administrator (67)”

I eventually came across this thread on the Apple Support forums which offered the solution below.

Goto Start Menu
Search for: security
Click on Local Security Policy
Goto Local Policies> Security Options
Double Click on Network security: LAN Manager Authentication
Change level to: Send LM & LTLM Responses

Then, scroll down to Network security: Minimum session security for NTLM SSP
De-select Require 128-bit encryption
Hit OK

This worked for me, now I get full access to my HFS formatted disk from windows 7 and all other computers on the network.