I had a similar error on filestream, writing to XML. It would work the first time, but the next time I would get an error, stating it was in use. After the write, I disposed and this resolved things. Not sure if that is the proper fix, but that's what I did.
Dim stream As New System.IO.FileStream(sAppPath, System.IO.FileMode.Create)
ds.WriteXml(stream)
stream.Dispose()
Load_Table()
James