The number of CPU core under your account is limited to 20 by default. If you see a red box like this, it could hit this limit. This limit is applied to # of CPU core, not # of instances. You can calculate the number by adding up CPU cores for each instance across all hosted services.
See below for further information. http://blogs.msdn.com/jnak/archive/2010/01/22/windows-azure-instances-storage-limits.aspx