Dim StreifenCMD As String = "SELECT kurz FROM magnetstreifen"
Dim SQLcmd As New OleDb.OleDbCommand(StreifenCMD, OleDbConnection1)
Dim SQLeinzelAdapter As New OleDb.OleDbDataAdapter(SQLcmd)
Dim StreifenDT As New DataTable()
SQLeinzelAdapter.Fill(StreifenDT)
cmbMagnetstreifen.DataSource = StreifenDT
cmbMagnetstreifen.DisplayMember = "kurz"

cmbMagnetstreifen.DataSource = Nothing

cmbMagnetstreifen.DataSource = Nothing
cmbMagnetstreifen.DisplayMember = Nothing

Zitat:

Hast du vielleicht DisplayMember gesetzt?