"Null reference exception was unhandled" o XP

I'm working on a project under VS2005 and .net Framework 2.0. Before that, I worked on a computer with Win7 x64 and everything was fine. But after moving on an old PC with WXP I've got a message: "Null reference exception was unhandled"


Dim dt2 As DataTable = ds2.Tables("clNumber")
Dim row2 As DataRow

For Each row2 In dt2.Rows '<<<<<< program stopped here
cboCity.Text = row2("City_Name")
Next row2

As I previously said, everything worked fine on Win7 x64.

Any suggestion?