Create Newsletter - This web page is not available

Setting the environment

Server : windows2003
wp : 3.5.1 (Multisite)
theme : MesoColumn
blog URL : http://blog.hyumc.com

error details

Whom it may concern,
After I installed the e-newsletter and finished setting the program, when I start the 'Create Newsletter', I get this message 'This Web page is not available' and the server temporarily freezes.

I deactivated most of plugins, but still the problem does not fix or solve.

I will be waiting for your answer promptly. Thank you.
Sincerely