nCover throws exception

First, I ran all tests successfully. Then I used nCover to generate report. The log is as follow:

[exec] NCover.Console v1.5.5 - Code Coverage Analysis for .NET - http://nco
ver.org
[exec] Copyright (c) 2004-2005 Peter Waldschmidt
[exec] Command: C:\Program Files\NUnit 2.4\bin\nunit-console.exe
[exec] Command Args: "build\classes\TopCoder.Notification.Test.dll" "/xml=l
og\TopCoder.Notification.Test.dll-coverage-unit.xml"
[exec] Working Directory:
[exec] Assemblies:
[exec] Coverage Xml: G:\tc\work_2\final_event_engine_2.0_dev_submission\log
\TopCoder.Notification.Test.dll-coverage.xml
[exec] Coverage Log: G:\tc\work_2\final_event_engine_2.0_dev_submission\log
\NCover.log.txt
[exec] Waiting for profiled application to connect...Connected
[exec] Configuring Profiler...
[exec] Program Output
[exec] NUnit version 2.4.0
[exec] Copyright (C) 2002-2007 Charlie Poole.
[exec] Copyright (C) 2002-2004 James W. Newkirk, Michael C. Two, Alexei A.
Vorontsov.
[exec] Copyright (C) 2000-2002 Philip Craig.
[exec] All Rights Reserved.
[exec] Runtime Environment -
[exec] OS Version: Microsoft Windows NT 5.1.2600 Service Pack 2
[exec] CLR Version: 2.0.50727.42 ( Net 2.0.50727.42 )
[exec] ....................................................................
................................................................................
................................................................................
................................................................................
................................................................................
................................................................................
................................................................................
................................................................................
................................................................................
.....................NotificationOneWayCallbackClient.OnNotificationComplete is
called!
[exec] .NotificationOneWayCallbackClient.OnNotificationCompletionStatus is
called!
[exec] .NotificationOneWayCallbackClient.OnNotificationRegistered is called
!
[exec] ..NotificationOneWayCallbackClient.OnNotificationComplete is called!

[exec] ..NotificationOneWayCallbackClient.OnNotificationCompletionStatus is
called!
[exec] .......NotificationOneWayCallbackClient.OnNotificationRegistered is
called!
[exec] ............................................
[exec] Tests run: 786, Failures: 0, Not run: 0, Time: 381.906 seconds
[exec] Unhandled exceptions:
[exec] 1) : System.AppDomainUnloadedException: Attempted to access an unlo
aded AppDomain.
[exec] 2) : System.AppDomainUnloadedException: Attempted to access an unlo
aded AppDomain.
[exec] 3) : System.AppDomainUnloadedException: Attempted to access an unlo
aded AppDomain.
[exec] 4) : System.AppDomainUnloadedException: Attempted to access an unlo
aded AppDomain.
[exec] 5) : System.AppDomainUnloadedException: Attempted to access an unlo
aded AppDomain.
[exec] 6) : System.AppDomainUnloadedException : Attempted to access an unlo
aded AppDomain.
[exec] 7) : System.AppDomainUnloadedException: Attempted to access an unlo
aded AppDomain.

.........

So I think there are problems in tests. How can I set the nCover to ignore exception? Please give me some suggestion for the possible reason. Thank you!