New blog template, redirect loop

Hi

Have just finished set up of first stage for new multisite installation.

1. Using Woothemes Canvas.
2. Sub domain installation & set up all went ok. Wildcard also set up ok for domain.
3. Created 1 x portfolio site on main domain and 1 x "network" site on sub domain which is intended to be the template for all following network sub domains.
4. Activated New Blog Template plug in in Network Admin >> made settings for first template >> Create = problem
5. Perpetual message "This page has a redirect loop" etc and cannot get to admin panel to identify anything, switch off plugin etc.

Seems to be much chat about redirect issues in general, but as I can be sure that it immediately followed this blog template process, would appreciate advice - a) how to fix log jam and b) avoid repeat.

Thanks