MelodyW:
I have one domain and two sub domains.
I can log in to the main domain admin area but can't log into the admin area on the subdomains. I have tried resetting the passwords but when I enter log in details just goes back to log in page - seems to be stuck in a loop.
Has anyone else had this problem?
I can think of a ton of reasons that would cause you strife in this scenario, and I'm thinking that this isn't what I would call a typical configuration by a long shot. It may be better/wiser if you could explain what you are trying to do or achieve, and we may be able to offer a better alternative?
There is nothing actually wrong with a setup like this, and it could be the best setup for your needs, in which case the solution to the problem will almost surely point directly back to your configuration files (which will be different for each of the domains and subdomains).
Be very wary of any redirects/rewrites in your .htaccess files. Mistakes here can be a nightmare to find and fix.
Cheers
Rod