Communication Issue with Allsky 340

I am receiving an error related to accessing Com port 2 on my Allsky 340. The error occurs at least once per day, sometimes more often. I'm using a new serial to USB dongle (US232R-10-BULK) the error is as follows with log file included. Assistance would be most appreciated:

Unhandled exception has occurred in your application. If you click Continue, the application will ignore this error and attempt to continue. If you click Quit, the application will close immediately.

Access to the port `COM2` is denied

See the end of this message for details on invoking
just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.UnauthorizedAccessException: Access to the port 'COM2' is denied.
at System.IO.Ports.InternalResources.WinIOError(Int32 errorCode, String str)
at System.IO.Ports.SerialStream..ctor(String portName, Int32 baudRate, Parity parity, Int32 dataBits, StopBits stopBits, Int32 readTimeout, Int32 writeTimeout, Handshake handshake, Boolean dtrEnable, Boolean rtsEnable, Boolean discardNull, Byte parityReplace)
at System.IO.Ports.SerialPort.Open()
at SBIG_All_Sky_Camera.SerialCommunication.WriteWCheckSum(Byte[] WriteData, Int32 Count)
at SBIG_All_Sky_Camera.SerialCommunication.WriteWCheckSum(String WriteData)
at SBIG_All_Sky_Camera.SerialCommunication.OpenCommunication(Byte COMPort, Int32 BaudRate, Boolean NoMessages)
at SBIG_All_Sky_Camera.formSettings.backgroundWorkerTakeImage_DoWork(Object sender, DoWorkEventArgs e)
at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e)
at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument)


************** Loaded Assemblies **************
mscorlib
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.3655 (GDR.050727-3600)
CodeBase: file:///c:/WINDOWS/Microsoft.NET/Framework/v2.0.50727/mscorlib.dll
----------------------------------------
SBIG All Sky Camera
Assembly Version: 1.0.35.0
Win32 Version: 1.0.35.0
CodeBase: file:///C:/Program%20Files/SBIG/SBIG/SBIG%20AllSky-340/SBIG%20All%20Sky%20Camera.exe
----------------------------------------
System.Windows.Forms
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.3645 (GDR.050727-3600)
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Windows.Forms/2.0.0.0__b77a5c561934e089/System.Windows.Forms.dll
----------------------------------------
System
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.3644 (GDR.050727-3600)
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System/2.0.0.0__b77a5c561934e089/System.dll
----------------------------------------
System.Drawing
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.3644 (GDR.050727-3600)
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Drawing/2.0.0.0__b03f5f7f11d50a3a/System.Drawing.dll
----------------------------------------
System.Configuration
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.3654 (GDR.050727-3600)
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Configuration/2.0.0.0__b03f5f7f11d50a3a/System.Configuration.dll
----------------------------------------
System.Xml
Assembly Version: 2.0.0.0
Win32 Version: 2.0.50727.3654 (GDR.050727-3600)
CodeBase: file:///C:/WINDOWS/assembly/GAC_MSIL/System.Xml/2.0.0.0__b77a5c561934e089/System.Xml.dll
----------------------------------------
KellermanSoftware.NET-FTP-Library
Assembly Version: 5.39.0.0
Win32 Version: 5.39.0.0
CodeBase: file:///C:/Program%20Files/SBIG/SBIG/SBIG%20AllSky-340/KellermanSoftware.NET-FTP-Library.DLL
----------------------------------------

************** JIT Debugging **************
To enable just-in-time (JIT) debugging, the .config file for this
application or computer (machine.config) must have the
jitDebugging value set in the system.windows.forms section.
The application must also be compiled with debugging
enabled.

For example:

<configuration>
<system.windows.forms jitDebugging="true" />
</configuration>

When JIT debugging is enabled, any unhandled exception
will be sent to the JIT debugger registered on the computer
rather than be handled by this dialog box.