"Logon failure: unknown user name or bad password" after user logon

In all versions of Directory Update and Directory Update v1.0 and v1.1, after a user logs on, you may see the following error:

An error occured.
Please contact your system administrator and report this message.
Logon failure: unknown user name or bad password.

at System.DirectoryServices.DirectoryEntry.Bind(Boolean throwIfFail) at System.DirectoryServices.DirectoryEntry.Bind() at System.DirectoryServices.DirectoryEntry.get_AdsObject() at System.DirectoryServices.DirectorySearcher.FindAll(Boolean findMoreThanOne) at System.DirectoryServices.DirectorySearcher.FindOne() at Ithicos.DirectoryUpdate.Common.ADHelper.GetDisplayName(String domainName, String userName) at Ithicos.DirectoryUpdate.MasterPage.GetCurrentUser() at Ithicos.DirectoryUpdate.MasterPage.Page_Load(Object sender, EventArgs e)

This error will look something like this:

This happens for one of a few reasons, all related to the service account. Here are a few things that can break this account:

1. The service account's password is wrong
2. The password on the service account is set to expire
3. The service account has been disabled
4. The service account's "Pre-windows 2000 compatible" logon name has been changed