Redirection to the same login

Hi,

I looked and looked for a answer to this problem I am having with one of my websites. I have a mess of sub-domains. When I log in to one of the sub-domains and then go to the next sub-domain I become logged out because as you know it’s a sub-domain, I want to be able to stay logged in whenever I go to these sub-domains. Any way to get around this with some sort of redirection fix, plug-in etc.? Thanks for the help.