Server error

[laasunde]

A bit of background; I've got an aspx web application that from time to time is unabled to load an assembly for some reason. This error can happen after running fine for many days\weeks. Its timing seems completely random at this point in time. The aspx source code is fairly simple

[PHP]<%@ Page Language="c#"%>
<%
AAClient.Server server = new AAClient.Server();
System.Xml.XmlElement status = server.GetStatus();
// transform and out xml
%>[/PHP]

This works 99.8% of the time. I see (using filemon) that the AAClient assembly is loaded by the webserver the first time the web application is ran and after that it re-uses that assembly (does not re-load or anything).

However, a few time I get this output when trying to execute the web application;

Server Error in '/SR' Application.
--------------------------------------------------------------------------------

Configuration Error
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: Unable to load file 'AAClient'.

Source Error:
Line 256: <add assembly="System.EnterpriseServices, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
Line 257: <add assembly="System.Web.Mobile, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
Line 258: <add assembly="*"/>
Line 259: </assemblies>
Line 260:

Source File: c:\windows\microsoft.net\framework\v1.1.4322\Confi g\machine.config Line: 258

Assembly Load Trace: The following information can be helpful to determine why the assembly 'AAClient' could not be loaded.

=== Pre-bind state information ===
LOG: DisplayName = AAClient
(Partial)
LOG: Appbase = file:///C:/Program Files/Company/SR
LOG: Initial PrivatePath = bin
Calling assembly : (Unknown).
===

LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Post-policy reference: AAClient
LOG: Attempting download of new URL file:///C:/WINDOWS/Microsoft.NET/Framework/v1.1.4322/Temporary ASP.NET Files/system report/f93a6e8f/6e6f7ce8/AAClient.DLL.
LOG: Attempting download of new URL file:///C:/WINDOWS/Microsoft.NET/Framework/v1.1.4322/Temporary ASP.NET Files/system report/f93a6e8f/6e6f7ce8/AAClient/AAClient.DLL.
LOG: Attempting download of new URL file:///C:/Program Files/Company/SR/bin/AAClient.DLL.
LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Post-policy reference: AAClient, Version=2.1.2.4, Culture=neutral, PublicKeyToken=null

--------------------------------------------------------------------------------
Version Information: Microsoft .NET Framework Version:1.1.4322.573; ASP.NET Version:1.1.4322.573

Judging by this output it seems like the webserver is trying to re-load the assembly. I thought that .NET and ASP.NET application could not re-load assemblies. Does that mean that the web application has been restarted and thats why its trying to load the assemblies again? What can cause an web application to restart?

The computer running this setup does not use index service, anti-virus or windows desktop search.

Running .NET 1.1 and IIS 5.1 ASP.NET 1.1