You arent using the novell client on your pcs by any chance are you?
We use to about a year ago, but we have now migrated to Active directory.
Another product we are running is called Imprivata OneSign -Single Sign-on (It's a Password manager). When it installs it replaces the MSGina.dll entry in the registry (HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\GinaDLL) with it's own authenticator. (SGLaunch.dll)