Query on User Authentication aganist ADS

[apondu]

Hi

I have a query, i have put the code here.

I am using VS 2005, C#.Net.

This is working fine when i am install the Win OS 2003 with ADS, but

after few days it starts entering the exception and gives the message
"

Logon Failure : unknown user name or bad password"

I am a bit confused and want to know the reason for this.

Can someone help me and let me know the reason and solution for this

because i cann't reinstall the OS all the time.
// Start of Code
using (DirectoryEntry deDirEntry = new

DirectoryEntry("LDAP://" + UserDomainTextBox.Text,
UserNameTextBox.Text,
UserPassTextBox.Text,
AuthenticationTypes.Secure))

try
{
string name = deDirEntry.Name.ToString();

MessageBox.Show("Welcome to '" + deDirEntry.Name
+

"'");

}
catch (Exception exp)
{
MessageBox.Show("Sorry, Invalid User");

}

// End of Code
Thanks for the help

Regards,
Govardhan