wp-admin This webpage has a redirect loop

I’m getting the error “This webpage has a redirect loop”, but only on the wp-admin Dashboard page. On sub pages to wp-admin I get 404 errors. For some reason the Network Dasboard works fine. My problem only started when I tried to move from one host (1and1) to another (dotster). My site if fully functional on my previous host. I copied my site up (including existing .htaccess) and loaded my database and ran the search replace script. One thing it may be related to is that my current site is http://www.mysite.com, and the new site is mysite.dotser.com (just until we go live). I have tried just about everything I could find on the internet related to that problem, and my new hosting company has said it’s a wordpress problem and no them.

Please help.

Thanks,
Joe