I have an admin panel made in ASP.NET C # webform. From a few days to now, he began to give problems of the type

Could not load file or assembly 'chat_megacorretor.dll' or one of its dependencies. The system cannot find the file specified.

The system hangs, however I just need to open the web.config add a blank space and the site goes back to running for hours, but then automatically crashes again.

Simply rename the file and go back to the original that works again, or upload the project file to the server. I know when I do this ASP.Net recompiles everything and so it works, but after a few hours to go again.

This same project worked for months, and now it started to give a problem, recently we did an IIS reinstallation from scratch, but I do not think that's the reason, because after the reinstallation it worked for about 2 weeks. But now it started giving trouble again.

In event view I find nothing interesting, just a few warnings .

I do not even know if they are referring to this problem itself:

Exception information: 
    Exception type: ConfigurationErrorsException 
    Exception message: It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level.  This error can be caused by a virtual directory not being configured as an application in IIS. (C:\inetpub\wwwroot\megacorretor\siga_2008\web.config line 16)

and also:

Process information: 
    Process ID: 12680 
    Process name: w3wp.exe 
    Account name: IIS APPPOOL\admin_Net 

Exception information: 
    Exception type: FileNotFoundException 
    Exception message: Could not load file or assembly 'CHAT_Megacorretor, Version=1.0.0.0, Culture=pt-BR, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.
   at Siga_2014.admin.Admin.DefineChatsWMB(Cliente iCliente)
   at Siga_2014.admin.Admin.Page_Load(Object sender, EventArgs e)
   at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e)