Erratic SMO behavior

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I hope this question might be ok for this forum. I am have the following code
below on a standalone computer and it worked perfectly. Suddenly, without any
significant changes to the code there were no "Servers" found on my local
computer. I know there are several server instance on the computer. Why is it
acting so unpredictable?
The same thing happened when I tried SQLDMO.

// Get a list of SQL servers available on the networks
DataTable dtSQLServers =
SmoApplication.EnumAvailableSqlServers(false);

foreach (DataRow drServer in dtSQLServers.Rows)
{
String ServerName;
ServerName = drServer["Server"].ToString();

if (drServer["Instance"] != null &&
drServer["Instance"].ToString().Length 0)
ServerName += @"\" + drServer["Instance"].ToString();

if (cmbServer.Items.IndexOf(ServerName) < 0)
cmbServer.Items.Add(ServerName);
}
--
L. A. Jones