I had problem some days ago with accessing my Windows 7 machine from another computer in our home network. When I tried to access my shared folders I was prompted to type in an username and a password, but I didn’t know either of them and therefore I looked up a way to disable the password protection. If you want to disable the network password protection to your Windows 7 machine (and maybe Vista?), follow these steps:
Start-button > Control Panel > Network and Internet > Network and Sharing Center > Change advanced sharing settings > Scroll down and check “Turn off password protected sharing” > Press the “Save changes”-button
Now you should be able to access your shared folders without being prompted for a password.