Hi

Actually I couldnt reproduce your senario, so I just could tell you the general reason why the application domain recycle.

• Machine.Config, Web.Config or Global.asax are modified
• The bin directory or its contents is modified
• The number of re-compilations (aspx, ascx or asax) exceeds the limit specified by the <compilation numRecompilesBeforeAppRestart=/> setting in machine.config or web.config  (by default this is set to 15)
• The physical path of the virtual directory is modified
• The CAS policy is modified
• The web service is restarted
• Application Sub-Directories are deleted (see Todd’s blog http://blogs.msdn.com/toddca/archive/2006/07/17/668412.aspx for more info)

Hope this helpful
Regards
Young Yang