Backgroundworker and Sql

I'm using a background worker to do some tasks that involve reading and writing to sql. But the main thread is also continuing to read and write to sql. And I am getting "There is already an open DataReader associated with this Connection which must be closed first." I've seen some talk about MultipleActiveResultSets. But I've also seen caution about them without specifics of what to do or watch for. Would MARS fix my situation?

Here is my current global connection to sql:

Code:

---

Public con As SqlConnection
...
ConnectionString = "User ID=" & strUser & ";Initial Catalog=" & strDB & ";Data Source=" & strServer & ";Password=" & strPassword & ";"
con = New System.Data.SqlClient.SqlConnection(ConnectionString)
con.Open()

---

When reading from sql I am usually doing something like this. This is where I'm seeing the problem.

Code:

---

        Dim comm As New SqlCommand
        Dim rs As New DataSet
        comm.Connection = con
        comm.CommandType = CommandType.StoredProcedure
        comm.CommandText = "ReadContacts"
        Dim adapter As New SqlDataAdapter(comm)
        adapter.Fill(rs, "Contacts")

---

Using vb.net, vs 2005, sql 2005.