Can not access Sharepoint site on domain member computer from external through IE

We recently set up a new intranet site using Sharepoint 2010.  Set up a forward to redirect the old intranet URL to the sharepoint site.  Set up policies to set IE settings to allow credentials from the account logged into the local computer to not have to log into the site.  Everything works perfect on domain member computers that are connected to the domain.  Everything works fine on non-domain member computers, the site comes up and prompts for a login.  
The problem is when the domain member computers are not connected to the domain.  When that is the case if the site is accessed through IE it goes to a blank white page.  If, on the same computer the site is accessed through Firefox or another browser the site prompts for login and then works fine.
We were pushed to set the site up in Sharepoint way before we were ready so we have very limited knowledge and experience in Sharepoint.  Have researched this and found several suggestions, mostly tweaks to IIS or IE settings, which have not worked.