2.0: unhandled exception after Page_Unload()

[R.A.M.]

Hello,
I have written simple ASP.NET application but during execution I got
unhandled exception. I have checked (debugging): it is not raised in
my code, it uccurs after Page_Unload.
Here's description:

Message: Exception of type 'System.Web.HttpUnhandledException' was
thrown.
Stack: at System.Web.UI.Page.HandleError(Exception e) at
System.Web.UI.Page.ProcessRequestMain(Boolean
includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest(Boolean
includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest() at
System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) at
System.Web.UI.Page.ProcessRequest(HttpContext context) at
ASP.default_aspx.ProcessRequest(HttpContext context) in
c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET
Files\mimmagazyn\64a9e8a5\4b2f62e8\App_Web_kqxbmtdn.0.cs:line 0 at
System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step,
Boolean& completedSynchronously)
Source: System.Web

Could you help me to solve this problem? I don't know what is going
on...
Thank you!
/RAM/