Help with an importation error

I'm trying to import CSV files into a database using ASP.net with VB and after one successful import I get the following error:

 

Source Error:





Line 57:
Line 58: Private Sub fillDS(ByRef file As String)
Line 59: oRead = oFile.OpenText(file)
Line 60: Dim linein As String
Line 61: Dim figures As Array
Source File: Z:\far\import_addition.aspx    Line: 59

Stack Trace:





[IOException: The device is not ready.
]
System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) +2056933
System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, ...