program crashes

[dreamdelerium]

hi everyone. im really in the need of some help here. if someone could look over this code and see any problems, please let me know. heres the issue im having, when the program starts, it runs just fine. but if left running, after about 20 minutes, the program crashes, with no errors (the vista error pops saying the program has stopped working and windows is collecting information). if i run the program in the debug mode, it seems fine.
some background: when the program loads, its spawns a class to check a device connected to a comport for status changes. when finished, it spawns again and again until the program closes. heres the code i have:

<Microsoft.VisualBasic.ComClass()> <System.Serializable()> Public Class Form1
Private WC As Class2
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
       
..onload event of the main form
.... other stuff that i dont think i a problem
....if i remove this bit, the program runs fine

        WC = New Class2

        ThreadPool.QueueUserWorkItem(AddressOf WC.FindMyPort)
        WC.Mycontinue = True

errorhandler:
        If Err.Number = 0 Then
        ElseIf Err.Number = 5 Then
        Else
            MsgBox(Err.Description)
        End If

    End Sub

end class

class two code:

Option Compare Text
Imports System.Windows.Forms
Imports System.Data.OleDb
Imports System
Imports System.Data
Imports GsmComm.GsmCommunication
Imports GsmComm.PduConverter
Imports System.Text
Imports System.Threading

Public Class Class2
Public Mycontinue As Boolean = True

    Public Sub FindMyPort()
        Dim storage = PhoneStorageType.Sim
        Dim MsgLocation As Integer
        Dim counter As Integer = 0
        Dim GetManu As String = ""
        Try
            comm = New GsmCommMain(9, 9600)
            comm.Open()
            IsConnected = True
            counter = 0
            Try
                Dim info As IdentificationInfo = comm.IdentifyDevice
                GetManu = info.Manufacturer

            Catch ex As Exception
                Thread.Sleep(6000)
                Debug.Print("error getting manufacutarer")
            End Try

            If GetManu = "huawei" Then
                Try

                    Dim messages As DecodedShortMessage() = comm.ReadMessages(PhoneMessageStatus.ReceivedUnread, PhoneStorageType.Sim)

                    For Each DecodedShortMessage In messages
                        MsgLocation = DecodedShortMessage.Index
                     '   ShowMessage(DecodedShortMessage.Data) 
'just a function to cop to db.  program crashes even if this is never called

                        counter = counter + 1
                        Thread.Sleep(1000)
                        Try
                            comm.DeleteMessage(MsgLocation, PhoneStorageType.Sim)
                        Catch ex As Exception
                            Debug.Print("error deleting from inbox")
                            Mycontinue = False
                            Exit Sub
                            Finally
                            messages = Nothing
                        End Try
                    Next
                Catch ex As Exception
                    Debug.Print("error gettting inbox")
                    Mycontinue = False
                    Exit Sub
                End Try

                If counter > 0 Then
                    NewMsg = True
                End If
            Else
            End If


        Catch ex As Exception
            Debug.Print(ex.ToString)
            IsConnected = False
        End Try
        Try
            comm.Close()
        Catch ex As Exception
            Debug.Print("couldnt close port")
            IsConnected = False

        End Try

        If Mycontinue = True Then
            Debug.Print("start new thread")
            Thread.Sleep(4000)

            Threading.ThreadPool.QueueUserWorkItem(AddressOf FindMyPort)
        Else
            Debug.Print("stopped")
        End If
        storage = Nothing
        GetManu = Nothing
        MsgLocation = Nothing
        counter = Nothing
        GC.Collect()
    End Sub
End Class

thanks for your help