I have an existing Multisite installation ( Version 2.3.9.7 MSSQL, Operating System Microsoft Windows NT 6.0.6002 Service Pack 2, ASP.NET Info v4.0.30319 Running in Full Trust) and am trying to add a new site.

I have added the new site details, and then clicked the Create button.  The "please wait" message has been showing now for about 2 hours.  Looking at the hosting space, the site folders have been created, but it has so far only copied about 22 of the skins into the skins folder.

Looking at the database, there is a record in the mp_sites table for the new site, but noting yet in mp_pages for that site_id

If I abort the process the site loads direct to the login screen, with no home page

Any idea what may be happening?  I have unlimited space on my Arvixe hosting, so that can't be the problem.

some times the request could time out or the application pool could get recycled while it is trying to setup the new site.

I would test the new site to see if you can log in, if so then copy any needed skins manually and proceed to create site content, otherwise you could try again and hope it works better this time. It may also be useful to review the log to see what errors might have been logged while it was trying to create the site.