How to create a Windows 7 fileshare that requires NO authentication

In the startmenu type secpol.msc, this will open the local security policy manager. Go to Security Settings -> Local Polices -> Security Options in there select Network access: Let Everyone permissions apply to anonymous users and set it to enabled. Then add the name of each share to be accessed anonymously on a line by itself in the setting named 'Network access: Shares that can be accessed anonymously'. Finally, make sure the Everyone group has permissions on your share and you should be good to go.

Caveat: You are on a domain, if the domain group policy assigns a value to this setting you will not be able to override it locally without the domain admin making a change to the GPO putting in a exception for your computer..

P.S.: Since you are on a domain, you may be able to do this by giving Domain Users permission to read/write to the folder, then anyone logged in to the same domain as you should have access. However this will not likely fix your network scanner issue.

I ran into this same problem just now and the help button on the share dialog actually (lo and behold) gave useful information:

Go to Control Panel -> Network and Internet -> Network and Sharing Center -> Advanced sharing settings and change Password protected sharing to off. See picture below:

I had the same problem between computers in my network - shares kept asking for a password.

It turned out that it was caused by having same usernames / different passwords between workgroup computers.

So anyone can access shares but if you have the same username / different password - you're screwed.