Multisite - login doesn't work when the domain is mapped.

Hi,

I have been at this for over a week and i can't figure out what's wrong, I have tried so many plugins first the free MU domain mapping, then multi-domains and domain mapping after buying the membership here and buying a dedicated ip. On every plugin i can always get the front end working and point the 8 domains correctly - I see the site no problem.

Login works brilliant without domain mapping enabled but fails everytime once it's enabled - I bought the domain mapping as is supports 'members to be logged into all sites within your network regardless of domain name' Hoping this would finally fix logins. The free MU Domain mapping doesn't support this i believe but i am getting the same errors even with the domain mapping plugin that does.

When a login happens the page just keeps loading and never refreshes or logins the user in.
I am really wishing someone can help me out.

To test
user: zenintest
pass: lolomg

http://vgmods.net < original site
http://vgmods.net/justcause2/ < multisite without domain mapping
http://dyinglightmods.com/ < multisite with domain mapping /dyinglight/

If you are logged out the site dyinglightmods.com loads, but if you are logged in the page is blank and its trying to authenticate nonstop.

Has anyone experienced this before? what can i do.

Many thanks to anyone who can help.
Kind Regards,
Amit